How can I map my alpha-ENTER to be the same as my numerical-ENTER please?

I'm using a 'standard usb keyboard' (that's what it says on the
underside anyway) and I'm finding that when using emacs as normal I can
only accept entries on my dropdown word-prompt (I type in 3-4 letters
and it pops up a list of possible solutions) using the numerical-ENTER.
Also if it shows a possible one-word solution for auto-complete by the
grey letters to finish the word, I can only accept using the
numerical-ENTER key again.

Hence my need for changing the keyboard mapping, but how please?

Thanks
Sharon.
-- 
A taste of linux = http://www.sharons.org.uk
TGmeds = http://www.tgmeds.org.uk
Debian 8.4, fluxbox 1.3.7, emacs 25.1.1