Help file for V11 is displayed in V10

I have tried V11 on a Lenovo G505 running Win8.1 (not updated yet). It was too slow (the G505 is a slow PC), so I decided to revert to V10, I think I used Windows system restore. But now, when I press F1 to get the help file, I get V11 help file instead of V10. Is there a way to fix this ?

Try reinstalling Opus 10.

Thanks. I did that and it works now.