I want to change my display resolution, but when I start radeon settings, there is no option available where I could change the resolution.
Not in Wattman...in your computer Display settings:
You change resolution using the Windows display settings.
it is also not working as shown in this picture.
I also can not find the tab "display" anywhere
Roll back to 18.12.3 till they fix the broken 19 version. Try DDU clean install the 19 series is an option though before rolling back.
Retrieving data ...