how do I transfer a tax file, that has been transferred from last year to my laptop, to my tower?

There is a post from "Just-Lisa-Now" dated 12/6/19 that looks correct (I did not test).  It reads as follows:

Install ProSeries on the new computer.

On the old computer, open ProSeries and highlight all your client files. Choose File > Client File maintenance and Copy/backup all the files to a flashdrive.

Open ProSeries on new computer.

Click File > Client File maintenance and choose Restore. Highlight all the files on the flashdrive and restore to the new computer.

Now run the Homebase Database Maintenance, that should sync HB up.

You'll then want to open the EF Center, highlight all your client files and choose to Update Selected Acknowledgements to pull all the EFile information into the new computer.

Note: If your laptop and tower are going to be accessible at the same time, you could always share the hard drive of the laptop with the tower. Then all of your files would be accessible from either computer, but only stored on the laptop.  There are pros and cons to this approach.

On the other hand, if you have the files on both computers, you have to manage file synchronization, and (as I recall) you also have to indicate to PS that you are using it on more than one computer so that you don't create duplicate submission ID numbers (or any other ID/tags that are automatically created by PS).