Canon of this show is not stable matter, don't treat it like one.
Basic World "Rules" and Lore



In nowhere, where concept of time and space doesn't exist, located TV station that has no stable form. Broadcast of it goes over every single of each infinite universes. Every. Single. One. In some signal is better, in some worse, but it is always there. Showing up on TV at random time, sometimes on internet, in your own mind... any gadget that can accept signal - can play it. Show can also appear as DVDs, tapes or flash drives in unusual places.
Keep in mind that show can be seen only life, so if you obtain DVD/fresh drive/etc "record" of show, it will NOT work in time when no one broadcasts. Good luck proving existence of this show to scientists when you show up to them 3 hours of white noise you have on that tape!
No matter that our audience is infinite (because universe is infinite yade-yade), spread of our signal works lowkey like a shotgun! In some universes it's normal, common experience to watch MindTV on friday evening. But on *your* planet Earth may be 40, or 10, or just 1 (one) singular person who has ever seen our program! So our "fandom" usually looks like lonely neocities page of some insane person... Wait a second...
Creatures, whose species is literally called "showpeople", make entertaining content that in it's base not far away from our "normal" media. Meteorology, News, Psychology, Travel, Music... a lot of show topics that you may have encountered on your not so anomal TV. But with a little twist. Meteorologists explain not weather on your planet earth, but stars deaths and starts of new black holes that scientists of yours probably haven't even found yet. News reporter, on other end, making broadcasts suspiciously related to you in specific, touching topics you'd prefer not to hear. Psychologists visiting your favorite media characters like Arthur Morgan or WX-78 and forcefully making them open up about worst fears they have. And many other stuff.
Being weird doesn't mean they have no rules. They all follow two main things, canon and viewer opinions. Let's start from the end. Viewers/audience - any person who, at this exact moment, sees Showperson directly or on broadcast. Their opinion is important because it can directly change how Showperson act, looks and sometimes even feel like.
Showpeople can NOT be audience, their opinion doesn't affect each other.

Viewers opinion

Let's imagine we have Tommy (showperson of meteorology) standing inside a room with you. You, for whatever reason, deeply believe she supposed to be green. Since you are only viewier at the moment, your opinion is 100% of viewers opinion. Tommy will listen to audience opinion and change into green. But I want to inform you, he will realize this is unnatural for him color, because of canon about which we'll talk later. What would happen if in room with you, green believer, and Tommy were other two people who count as audience? Well, now your green opinion is opinion of only 1/3 of audience, less than half! That doesn't worth changing anything, so Tommy won't change to green color. If you, sick freak, still want to make them green, you need to become more than half of audience. So you either kill other two, making yourself 100% again, or make at least one of them join your green cult. 2/3 is more than half - Tommy will become green.
But what happens if showperson is not perceived by anyone? And what stops viewers from completely changing everything? And how will Tommy know her green look isn't natural? That's where canon kick in...

Canon

Canon is original and untouched by headcanons look of our showpeople. Showpeople are ALWAYS aware of canon, and it is not something viewers can change. You can't make showperson forget about how they should be, but you CAN make them feel different about their canon and manipulate their opinion. So Tommy will always know he aren't originally green, but you can make him agree that green suits him more.
But to do so you first need to know about it... Viewers opinions usually don't affect showpeople as much as in green example. If you meet Tommy without knowing all these rules beforehand, you most likely will have opinion about him based on how he presents himself. Even if you think for a moment, "Damn, i think it would suit her to be green", just thinking about it for a moment won't change anything. You need to purposely fully believe in green gods, and most likely you won't do that if you have no idea you even can do so, right? So most showpeople stay loyal to their canon even when they talk to audience. They may change in little details, but not extremely so.
Most, but not all, of showpeople learned to not spread about viewers opinion power too much to avoid it being abused against them. But what happens if they do and viewer starts to do not very nice things to them? You kidnaped now green Tommy making them wear maid dress and call you daddy, who gonna stop you?
VIP viewer - Sam, one of few workers of MindTV who is NOT a showperson. They are "censor". He's not often do what you expect him to do, ban tits and cocks from tv, and much more often taking care of canon staying canon. Opinion of Sam is above any other audience, no matter how many we have. There may be 143246 people think Tommy is green, but Sam will overpower them all. So she will show up, beat you up, and take Tommy home.
Last thing to notice about canon... It isn't stable. Time to time it changes, some time unnaturally and significantly. Noone knows how it happens and what is source of it in first place. It just how it is.
Now let's talk not about how world may affect showpeople, but how they may affect this world back. Showpeople, unlike what you may expect, usualy avoid changing reality. "But hey!" you might say, "I've seen Doctor Carl during his show showing up in scp universe and magically turning 079 into a duck! That sure is 'change of reality'!" But that isn't much true. You see, they are performers, and what they do is just a show, not reality. When Doctor Carl visits another universe, he actually creates... new sub-universe in which he performs. It's a stage with props identical to universe he portrays. After he leaves, props will be removed and this universe stops existing.
You can see visual explanation here:
In these props-universes powers of showpeople is almost infinite, because all characters in them are not real, which means they are unable to be audience and use their opinions. Showpeople are capable make it look and act in way they want to make show more interesting. That is safer and often more convenient option in case where point is just intertaning.
But I do want to notice that some showpeople prefer life-reporting. For Tommy, it is important to show real stars in his show, not replica. And what if some of them decide to do life event? Like if May_Day perform life concert? Showpeople prefer, but not limited to always using sub-universes in their shows. They can enter and interact with worlds that don't belong to them, but their powers would be much more limited. In some way Showpeople is a mirage, strong television signal that affects mind so strongly they get physical form, their powers work equally. Doctor Carl may show up in your world and create huge monster that will chase you around breaking buildings, but it will not be real. All buildings will stay intact after show, and you, if we exclude heart attacks, are unable to get phisically damaged.
There are more details, but for now I believe it's all you need (I'm tired). Instead of all this autismmaxxing, let's give you something actually important! Go to next page about...
!!!CHARACTERS!!!