i try to edit my replays, but before i can save it, it stops replaying and i lose all the progress, is there a solution besides turning autosave on ?

If it's single player then you just need to not press space before saving. If you're on a laptop it's possible you're accidentally catching a hotkey (some have space + another key mapped onto them)

If it's multiplayer then you just have to be quick to save or use autosave to guarantee getting it.