Personally I have reservations about the merits of transferring your preferences from one version to another. It's possible for Preference files to get corrupted over time. Hence the frequent suggestion for solving strange problems by doing a "Factory reset".
If you recreate your preferences from scratch in a new version you are starting with a "clean sheet". Obviously to do this you need a record of your settings and preferences. I keep a text file record which I can print out for ease of reference.
I'm with @EricLNZ on this. I have to, with each version I've upgraded to, set up my Windows, go through the Preferences making sure that everything is checked that I want (because they add new features sometimes), I have to go through the Customize Toolbar at the top. I do wish that everything was alphabetized though, oan showing all the Visible Buttons on the tracks and clips.
Yes, it takes a bit of time, but then I am sure that everything is right where I want it to be.
Having no issue at all importing previous preferences (and that are quite a lot, including several UI layouts) into a newer version of Vegas. It would take me hours to do that each time manually. It's a pity that not all customizations are taken over like customized toolbars, customized shortcuts etc.
Ofcourse you can do that each time manually when you prefer to do so, but that wasn't the question...
If you do transfer preferences from one vp to another on the same machine using export and import, that will cause all kinds of problems with saved Vegas window layouts. Because Vegas saves the version-specific paths for the layouts in the export. You could edit the export with Notepad and change the paths to point into the newer version. And go even further by copying the old layouts from the folder in the older version to the corresponding one in the new version... that usually works if the new version didn't change the layout formats but it's a good idea to resave them with the new version anyway. I find it wiser to just write down all my custom settings and re-implement them manually in the new version as part of my get-acquainted process.
Btw, if you try to import settings from one machine to another, even if the Vegas versions are the same, you also have to account for any login identity differences which are also embedded in paths.