Question about Flash Course 3: Is it only one attempt? I didn't see that in the rules, but it keeps autoloading my replay and I don't see a way to start over. Is there a way to reset to the beginning?

You can attempt as many times you please. Submitting replay overwrites your previous submission.

if you click "continue" instead of the "exit without saving" it creates autosave called "--eventtmpflashcourse3.rpl" to your my replays folder. It doesn't show up in game, but if you navigate to that folder from game files and delete the replay file, it won't auto input that previous attempt anymore.

One quick way to get fresh start is also letting the autosave fill in the moves, pressing "R" to enter replay mode and then "space bar" to start new game.

You could also just load the mod in freeplay, do it there and load that replay in event after. That way you can avoid couple bugs that the event one has (ctrl+z) works there and no risk of it starting edit mid viewing replay. But there you won't see those checkpoint for example, so doing it on freeplay has downsides too.

Ah, very helpful, thanks! Hopefully this info will help other in the future as well.