Kodi resolution issue

I have a huge resolution problem, with huge I mean I litterly cannot fix this.

with the DESKTOP resolution or the highest listed resolution which is 1920x1080i I am missing a little bit of kodi on all edges.

If I take a smaller resolution so it does fit, my screen goes spacing every 10~15 seconds. It goes black, flashes purple, goes black again and than goes back to ‘normal’. I would not want to have this reso anyways cuz it looks like garbage.

I have tried the video calibration thingi in the advanced settings. But that does not effect the menu size at all.

I suppose I need to do change something in a config.txt somewhere, but I do not know howto. Can somebody help me out?

The Tv is an Mt logic TFT 3264HD, I’m using a Rpi 3 with latest Raspian, and I sudo apt-get installed kodi.