keyboard settings changed after windows 10 intallation

I use Acer aspire one D257 netbook with windows 7 starter edition. Today I upgraded to windows 10 home edition. There after my keyboard settings for Fn key has changed and 4,5,6,1,2,3, etc have become default buttons and u,i,o,j,k,l, etc have become fn buttons, even now I am typing after pressing fn buttons.
how to rectify this? Should I go back to windows 7?

Have you checked, if Acer offers updated drivers for Windows 10 for your model?

It might be that hitting Fn four or five times toggles it back to normal, but if it does basically depends on the model/driver.

Somewhere in the control panel, Windows has a StickyKeys option, which you should be able to find through the Windows search - search for "StickyKeys". Maybe toggling that one helps.