Minecraft: Who knows this problem?

Ca
1

I have a problem with Minecraft:

If I press F11, Minecraft will be smaller or larger.

My problem is that if I want to make Minecraft big again, Minecraft will appear on the screen top left only a quarter as big.

Then I have to restart Minecraft to make it look right again.

Can anyone help me?

First many thanks and best regards

Re

Graphics card failure?