From POP3 to IMAP to POP3 problems

I had a problem with inbox subfolder synchronization from e-mail server using POP3. So, I changed the e-mail setting form POP3 to IMAP. I was able to operate with my subfolders now, but I had problem with older e-mails as POP3 downloaded them and made them unreachable. I created the backup and exported all emails before a did a change from POP3 to IMAP.
I have decided that the best solution would be to go back to POP3, due to limited storage capacity of my e-mail server. So, I exported e-mails so that I don’t lose any new e-mails in my inbox and changed the e-mail setting from IMAP to POP3.
Now I was hoping that the new POP3 setting would be able to reach old data of previous POP3 and bring back all downloaded emails, but that did not happen.
I would like to ask you, what is the best next step for me to do?
Thank you in advance for your answer.

POP3 doesn’t sync with the server. You won’t get any of the folders on the server, you will only get new messages.

Unfortunately you can’t do that. You will need to setup a new account manually as POP3, move any messages across from the IMAP folder, then remove the IMAP account. Full instructions on manual setup are in the Documentation (F1) under Getting Started.