The best you can do is to “compress” the track so that it remains at about the same level throughout. That will make the quiet voice louder when it is on its own. It will not help when both voices are speaking at the same time.
I love Auphonic for this. I think you can still get a free account with two hours of processing per month, so there is little risk in trying it to see if it will solve your level problem.
Considering that the original poster has been banned for spamming (not a genuine user), there’s really no need for further replies. I am therefore closing this topic.
As this is the Audacity help forum, solutions to problems using Audacity are much preferred to solutions that use commercial software or commercial services.