Lol thanks, but honestly I'm just trying to understand the game as much as everyone else
So unfortunately this game currently works on an autosave system, which triggers after you complete any of the morning activities (work, gym, etc.). To "undo" a wrong choice you've made at that moment you will need to immediately quit the game asap (CTRL + ALT + DEL to go into task manager and force quit the game). As long as you haven't slept in bed and completed the following day's morning activity you should be good and now have a chance to redo the previous day. If not, and you've already autosaved, then sadly there's really not much you can do from here on out. I read somewhere that the game dev plans to implement an actual save/load system, but there's no ETA for that so being extra careful with our choices is the only way to proceed for now. (Almost feels like a Dark Souls game as weird as that may sound lol.)
As a side rant, I really wish the game dev took more care in ensuring players don't get locked out of content. Even a warning hint would've sufficed. For example, it's possible to not get all the photos for Anna's Wardrobe event if you gain too many subscribers too fast, because once you unlock her Basement studio she no longer goes to the Wardrobe with the exception of a scene or two. Furthermore, it's possible to miss the third/last photo in the Warddrobe if you fail to give her wine at any point in the week!