games refuses to go into fullscreen mode ? any fix if not this is a return for me

I don't know, but you can try this link to see if any of these threads cover the issue:

https://www.gog.com/forum/pillars_of_eternity?search=fullscreen

Note that each game (or group of related games) has its own subforum here on gOg. The one for Pillars is:

https://www.gog.com/forum/pillars_of_eternity

Good luck with the matter.