It’s good, I use it all the time, so much quicker to change speed than default way.

But when an ad comes up it resets speed to 100% again. If I change the speed with the normal YT changer it will not reset. Is there any way to fix that please?..

I'm using these 2 add-ons to deal with YT ads:

YouTube Ad Auto-skipper
Mute Youtube ads

- and I thought it was maybe one of those doing it but I turned them off and it still did it.

So there must be something different about the way this add-on changes the speed compared to the default YT way that is causing the issue.

Simple and effective

Very simple but very handy.
To control speed hover over icon(left near Autoplay icon) and scroll the mouse middle button. To reset to normal speed just click left mouse button on icon. Fantastic! ))