If you have my plugin pack installed, try using Adjustments > Hue/Sat+
Just start with a general selection, then run the effect:
After setting the controls at the top to select your brown frame, use the Hue Adjustment to change the frame color.
Unfortunately, there is no way to: copy everything I just did to this image to another image. You will need to look in your history, make notes, and reapply everything one by one.
Here is a classic script to help you determine when you are on the edge of a selection...
So, select your building outline and run the script.
Hope this helps.
Since no one else is reporting this problem, i’m going to have to assume that it is your computer that is the problem. I would start by doing all of the windows updates. See if that helps.
Are you running the Classic (free) version of Paint.NET or are you running the Store (paid) version?
Installing plugins is different based on which version you are running.
Read this: https://www.getpaint.net/doc/latest/InstallPlugins.html