How do I change the default browser in Windows 11?

After going back and forth in the settings, it appears there is a bug (in preview build 22000.51 at least). There were two file types that were not shown previously, .htm and .html. After setting these, Firefox is now the default browser.

I tested all file types and the crucial ones for Firefox to consider itself the default browser were .htm, .html, HTTP, and HTTPS.

Conclusion

So in conclusion the answer is to go to Settings > Apps > Default apps > scroll to and select your installed browser of choice (Firefox, Chrome, etc.) and associate the file types or link types:

• .htm
• .html
• HTTP
• HTTPS
• ...and any others you wish to open with your preferred browser