How to set code versions activity in Google Play Console?

Solution 1:

(I never though PlayStore keeps active an old version for very old SDK users...it's strange Google does it because if you release a newer version it should be take in count about old users in your new code and not by a complete old and separated version.)

At this time you can't change something of previous releases. Unfortunately PlayStore doesn't more accept updates that targets SDK<26 so the only think you can do is take in count SDK between 16 and 25 in your code while targetting 26+.