Mods, feel free to move this to the fanedit section if you deem it more appropriate. You can include spinoffs if you want, although I won’t. I’ll go first.
TPM: Make Anakin 10 years older.
AotC&RotS: Make all the Jedi’s lightsabers blue.
ANH: Include the scene of Luke and Biggs on Tatooine.
TESB: Clarify the timeline.
RotJ: Make the other Vader instead of Luke.
TFA: Have the film end with the shot of Luke tossing his lightsaber away.
TLJ: Pick a different title.