Ctrl+1-9 cannot be disabled

[whateverthefug]

Selecting Ctrl+1 Ctrl+2 Ctrl+3 and the option to 'Do nothing' to disable switching tabs with these keyboard shortcuts doesn't function, the tabs will still always change.

[harl]

I just did exactly what you described and it works fine for me.

Don't forget that you need to add each of those shortcuts separately, then save them, then REFRESH the page(s) which you use the modified shortcuts on, just as the extension's description explains it. (Recommended action is to either refresh all tabs - or just restart the whole browser, so that all pages are unloaded.)

Also, add-ons / WebExtensions don't work on (addons.)mozilla.org and certain local pages like moz-extension:// etc. That means default shortcuts can't be overwritten on those pages either.