For both the original trilogy and the sequel trilogy I use the title (well, except the first, which I just call “Star Wars”) while the prequel trilogy I use “Episode _”. I might also prefix “Star Wars” to the sequels if I’m bringing it up out of context.
And that’s not really a conscious decision on my part, it’s more that, frankly, that’s what they’re called. Well, technically the prequels had the whole “Star Wars: Episode _ - The Rest of the Name,” but you look at the logos with EPISODE BLANK in huge text and the rest all tiny, it’s clear what the “main” title is, while the rest is relegated to subtitles (and I do recall most people referring to them as “Episode _” or sometimes “Star Wars Episode _” in conversation, with the exception of certain Star Wars fans when talking to each other).
I’m a little skeptical of the idea that they ever REALLY changed the names of any of these movies. Like, if we were to go look them up in national film registries or whatever, they’d all have their original titles and I doubt the stakeholders would actually want to change them. I think they have a “marketing title” that is fluid with the times (note in the years the sequel trilogy was in its various theater runs the prior films all retroactively became “Star Wars: The Name of the Movie” to match, eliminating the “Episode _”; nowadays it seems a bit more loosey-goosey), but the release title is sort of the “primary key” of sorts.
I’m probably not describing anything us long-term fans don’t already know, but I’m pretty sure these are still the ULTRA OFFICIAL IF YOU WANNA GET REALLY TECHNICAL ABOUT IT titles of the movies:
Star Wars
The Empire Strikes Back
Return of the Jedi
Star Wars: Episode I – The Phantom Menace
Star Wars: Episode II – Attack of the Clones
Star Wars: Episode III – Revenge of the Sith
Star Wars: The Force Awakens
Star Wars: The Last Jedi
Star Wars: The Rise of Skywalker