Firefox forces itself to be default browser
When I run Firefox, it makes itself default browser automatically. In the General Options, the check box for "Always check if Firefox is your default browser" is marked and readonly, grayed out, so I can not unmark it. I am on Windows 7, Firefox version: 52.3.0 (32-bit) I tried uninstalling and removing all the related folders then install again. Problem continues.
Looking at Control Panel\Programs\Default Programs\Set Default Programs Before I run Firefox, it says This program has 0 out of 9 defaults. After I run Firefox it says "This program has all its defaults".
Note: Some software, like Advanced SystemCare with Surfing Protection, can protect files in the Firefox profile folder against changes. If you have such software then check the settings or uninstall this software.Read this answer in context 1
Additional System Details
- User Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.101 Safari/537.36
Have you tried completely uninstalling Firefox, setting your default browser of your choice and installing the newest version of Firefox? That might help you out with the issues.
Note: Some software, like Advanced SystemCare with Surfing Protection, can protect files in the Firefox profile folder against changes. If you have such software then check the settings or uninstall this software.
I run Windows 10 and Firefox 57, use ZoneAlarm and Malwarebytes, and my default browser box is grayed out and unchangeable.