How to sync Thunderbird emails, over two computers?

There are several answers to this question but none seem to reflect my problem.
I have recently installed Thunderbird on a new Laptop, I have copied the profile and I can see everything on the new machine everything works ok.
However if the PC reads the mail it appears in the inbox ok, but it can’t be seen by the laptop. Similarly if the laptop reads the Email it can be seen on it but not on the PC.
I use an imap server on both machines.
Is there any answer to this please.