Youtube Ad free : green button not working

So I went through all the lengthy installation for Youtube Ad Free (see here). After a first hiccup (the app wouldn't install from the tv, I had to install it thorugh the Webos Dev app on my pc), I managed to get it.

But when the app is open, the green button doesn't open the setting menu as expected.

And some sponsored ads still show up.

Would you have any idea how to get access to the menu?

My tv is an old LG UH8500 with WebOs (last firmware update 05.70.30)