AASTRA DT292 for MX-ONE User Guide EN - Manual (Page 86)

Settings
DT292 86
Display contrast
You can adjust the contrast of the display to one of eight levels to
make it easier to read.
Route: Settings » Display » Contrast
Contrast
Select. Ь Ы
Press.
The contrast level bar appears. L
or
M
Adjust the contrast.
You hear an error beep when either limit is reached. Ь Ы
Press to confirm.