@sussymist If you run a program as administrator then later try to run it as a normal user, this is what can happen. Most obvious answer: close Opera GX, use File Manager to delete or rename your profile directory (I'd rename so that you might be able to restore your original settings later), then restart Opera GX so it can create a new profile.
Before doing any of that, go to Help > About Opera, then highlight and copy the path listed for your profile - that way you can just paste it into File Manager's location bar. If File Manager tells you that you need administrator access to rename the folder - it should, normal users aren't allowed to just change administrator settings - then just confirm it.