Solved Possibly being phished? - Help!

Will resetting my router make me set-up my wireless password again? Because I am not sure I know how to do that.
 
I have not reset my router, but the popups have not happened since I uninstalled Steam. Do you think re installing Steam will make the popups come back?
 
Well thanks anyway argus, you were a great help. You can mark this down as solved, because I believe the issue is in fact steam.