Hello,
The issue with the volume disparity between the video and the commentary usually requires enabling a feature called Loudness Equalization, which keeps volume consistent.
However, since you lost your Bang & Olufsen controls after the upgrade, it sounds like Windows 11 installed a generic audio driver instead of the specific one for your laptop. That software (B&O) actually runs on top of the Realtek chip, so you need the specific driver to get that control panel back.
Could you post the specific brand and model number of your laptop? That will help locate the correct audio driver that includes the B&O software.