Several years ago (5+) I used some obscure Firefox settings to enable some sounds for the right click "Context menu" appearing and selecting an option for said context menu. These sounds also apply to the menu bar drop-downs at the top of the browser window (Disabled by default.) I enabled these because, at the time, Firefox stopped using the native windows rendering for the context menu and menu bar and thus stopped triggering the built in windows sound API calls. Later updates however have made this a bit of an issue as Firefox plays these sounds at full volume now while I have the windows sound effects reduced in volume compared to overall system volume. These are not native windows 7/10/11 sound effects I am using and are quite harsh and slightly painful at full volume, and while reducing the volume of Firefox itself in the windows 10 sound mixer is effective on them, that simply isn't a solution due to the volume of media content in Firefox (eg: YouTube) being affected as well. I have since tried to find again the guide/article I used to enable these sounds, and manually find the value in About:Config where I believe these changes originate (I could be wrong on this), both to 0 success.

Does anyone know what obscure changes I need to make to remove these sounds?