Borderless becomes windowed mode?
Windows 10 Running on a laptop (Maybe integrated graphics problem?)
Windows 10 Running on a laptop (Maybe integrated graphics problem?)
Laptop specs would help, and when does it happen? Can you change back in-game?
League has a bug that keeps resetting your settings to windowed everytime you log in, You just gotta keep switching it manually in the beginning of your first game every time
EDIT: Not your fault, it started happening mid-2018 to almost everyone I know.