only one option keeps being reset after restarting computer

I always play on Borderless, ever since 1 or 2 patches ago though It's been making my matches start in Windowed mode. I switch it to borderless back and the following match that league session stay Borderless, until I restart my computer and then the very first league match again starts in Windowed. I tried looking through forums to find a fix which I thought I found one, it told me to: C: > Riot Games > League of Legends > Config Delete Files : PersistedSettings.json (and another File I forgot the name of) I went into a custom match to re-do all my settings, exitted custom after saving settings. Went into a real match and it all saved (now to restart my computer and see if it actually fixed my problem) I restarted my computer, logged into the game and started a match, it started in Windowed still, not Borderless.... any1 know what's up?