Hello everyone, I stumbled upon the problem of a new episode not recognizing the previous games, so I tried to find a fix.
Apparently, copying the files from the old save location to the new game's one worked.
So, what I did is:
going to "C:\Users\USERNAME\Documents\Telltale Games\The Walking Dead"
copied all those files
then pasted them to "C:\Users\USERNAME\Documents\Telltale Games\The Walking Dead Episode 3"
This worked for me, and now I'm getting a new game with the previous decision.
Hope I helped.