Just got my Wheeltop cable brake groupset from Aliexpress. Easy to install on the bike. Went to initial install the rear derailleur.Llined the rear derailleur up with the small cog and set the limit screw then wanted to set the limit screw on the large rear cog and could only get the derailleur to move to cog 8 on a ten speed cassette. After a lot more fiddling and frustration the rear derailleur is stuck on the large cog at the back. On the app this is shown as gear 1. Somehow I have moved the starting gear as the large cog. Not sure how I did this. Is there a simple way to return the derailleur to its original setting (reset button) so that I can start all over again or is there a simple way of getting gear 1 back to the small cog on the rear cassette?

Also is there some easier set up instructions for the gearing?. The Wheeltop manual is pants and confusing!!

Any help greatly appreciate