Seems to me that something changed since last update, while I'm watching udemy corses, and when I jump to the next course, the volume reverts to 100%, but I have it set to 200% (and I see 200% in the extension) ?

Absolute necessity. Two issues:
One, the volume often resets to 100%, tho the toolbar button will continue to show a higher volume. The slider itself will be back at 100. Two: It would be great to have hotkeys to adjust the volume without clicking the button. Then I could set my touchpad to adjust the volume with gestures.
BTW, I reviewed all of the code and didn't see anything to worry about it.

Not work on open.spotify. Unknown .js script in code.

Excellent would be great if it stays at the same level for each website so that the volume neednot be adjusted for each tab

Straight forward, small and works like a charm.

I use this add-on more than any other.

works great ...very happy with it...no problems at all....recommend it ....

Very useful extension if you want an extra volume boost to your cheap weak speakers.
One little bug: the number on toolbar button doesn't update when I change tabs, so it looks like it's a different volume. It only updates when I click on it.

Does it's job well.

I don't know if it is really 600% I don't really have a way to measure but it 100% works. I have horrible hearing and hate headphones.