[Potze]

I can't change it from 1024×768 to 1920×1080 in Menu, it shows nothing and goes automatically back to 1024. If I start an film with 1920x1080 the screen changes to full hd.

Can you ssh in and run "tvservice -s" when playing the video and when switching to 1920x1080 from GUI?
It's quite likely the refresh rate (or other settings) is different in the two cases.

When playing a video in 1920x1080:
"state 0x12000a [HDMI CEA (31) RGB lim 16:9], 1920x1080 @ 50.00Hz, progressive"

When in GUI:
"state 0x12000a [HDMI CEA (4) RGB lim 16:9], 1280x720 @ 59.94Hz, progressive"

When changing from 59,94Hz to 50:
"state 0x12000a [HDMI CEA (19) RGB lim 16:9], 1280x720 @ 50.00Hz, progressive"

Chainging to 1920x1080 (59,94Hz):
"state 0x12000a [HDMI CEA (16) RGB lim 16:9], 1920x1080 @ 59.94Hz, progressive"

I tried to change to an resolution that is less, the same happens.
Skin is Estuary.

greets

I found the problem and the solution:

I am using an AV-receiver ( Pioneer V-923 ) and the time to change from one resolution to another will take about 23 sec.
So I connected the rasp direct to the TV and changed the resolution, under 5 seconds I get an screen and check the box.

Orignal connected works fine.

greets