Welcome to the SeeMeCNC Community

Yesterday I tighten my belts a lot and I printed 0.5 thick wall calibration cube. It comes up very ugly. I think the belts was to tight. when I measure temperature of X,Y,Z drivers on the RAMBO it has about 90 C. So I losen the belts. Can anybody post a picture or try to describe the proper tension of the belts in for example end stop position.

Second thing.
After print I also measure the extruder driver and it has about 85C. It doesn't have any problems with extruding, it's very smooth. Is that normal?

The driver temperature is not dependent on how hard they are working, it's dependent on the digipot values in the firmware.
if you home and wait they will get just as hot as they do while working.
The default digipot values are quite high ~1A and the drivers do get hot, they have thermal protection, and will intermittently cut out if they get too hot.
I have a 40mm fan on the back of my board, and next time I put in an order with ultimachine, I'll pick up some heatsinks but it's probably not necessary