Won't remember login

I download mods for fun and to use on anarchy servers, and I know the risks of jars and token logs. I don't know whether this may have to do with the fact that I keep having to log in upon re-launch of Minecraft, which I do very often because I switch between modded 1.12.2 and 1.8.9. Either my account might have been compromised, or this may be a bug with the new launcher. It should be noted that I do not use vanilla clients for either. (Forge and Lunar)

Steps to reproduce:

1. Run minecraft
2. Close minecraft
3. Run on different/same client