Problem speeding up youtube on windows.

Hi all,
I'm using windows 11, latest version of firefox and NVDA. I have a problem on youtube, where sometimes the >(greater) key command for speeding up the video doesn't work, and the speed submenu has two radio buttons "normal and custom. When I try to click on the custom button, (I can see that there is a slider, and presumably I'm suppose to slide that slider to the speed I want) it doesn't work, I can't move the slider at all. The trouble is, the appearance of this submenu is unpredictable, one minute a video has this new speed submenu, but if I close and come back to the same video, I have the old one. So even if I wanted to report this to youtube, I'm not sure how. So my question: how do I work with the new slider, or make sure I constantly have the old one? I've tried pressing nvda+f2 to send the combination directly to the application, didn't change anything.
Thanks