The problem is resolved. I tried to take many single steps so I could discover the cause, but I don’t know what finally fixed the problem. I did the following: 1. Uninstalled Brave with program that is supposed to remove all related files. 2. Installed a new copy, with no bookmarks installed and the problem remained in my original profile. 3. Created a new profile and as before found YouTube volumes good in the new profile 4. I opened my original and the new profile and opened to “settings” in each one. One at a time I laboriously changed an original profile setting to match the new profile. I closed the browser, and reopened it to see if volume had changed in my original profile. 5. Finally, way down in the System setting category I turned on and off the “Continue running background app”, and I turned “Use hardware acceleration” on and then off, After exiting the browser and then restarting it, volume on YouTube was normal. 6. I added two extensions, one at a time, and YouTube volume was still ok. 7. I imported my saved bookmarks and volume still continued to be normal. I’m sorry I don’t the exact step that eliminated the problem. I noticed this installation of the latest browser I downloaded doesn’t have my picture in the upper right corner; now it’s a color filled circle with a white X, so something is different about the latest version.