POP only connects to the Inbox. You need to use IMAP to sync other folders. As usual your provider help desk gave bad advice.

Thanks Airmail. So would you advice to change settings to imap. the advice from sky is to set all the others as imap but thunderbird as pop. Which seems a bit daft

Some users do that by choice. They appoint one computer as "master" and use it to manage what's kept on the server. But they would normally use POP on all their clients with them set to "leave messages on server". Mixing IMAP and POP always seems somewhat unsatisfactory to me.

And most phones and tablets really don't make sense with POP; they can't afford to just accumulate email with their limited memory capacity.

Don't "adjust" your existing account in Thunderbird; set up a new one to use IMAP.

Thanks Zenos for your reply as well. How do you mean "don't just adjust" your existing account set up a new one. I have already deleted the account and set up a new one with original settings and in the process lost all the saved emails. Is there a way of saving the emails and then putting into the new account?