Hi Marco !

You have 2 ways to upgrade:

1) Compile by your self. It is actually rather easy after you have installed all needed packages for compile.
See this message: https://cqrlog.com/node/2998 Compile with your old Mint goes same way. Note that you need to follow the message only from start up to line "So far success!" The rest of it explains how to activate QT5 and it is not needed in your case.

2) second way is to install (or if you have already running) latest version of cqrlog that you can have. After that go to https://github.com/OH1KH/cqrlog/tree/loc_testing/compiled Read the README there. Briefly; download newupdate.zip", extract it to find newupdate.sh, start it in command console and when it is running select update of 32bit version. Script will do the rest of the job.