You can try this add-on. https://addons.thunderbird.net/en-US/thunderbird/addon/manually-sort-folders/

The add-on cited above is the easiest option, but if you prefer to do it without an add-on:

https://www.ghacks.net/how-to-sort-accounts-in-the-email-client-thunderbird-manually/

SFhowes. This link is from 2015 and for the old version not the new one. Thanks anyway.

Christ1. Thank you but I am not sure what to do when I click on the link and it asks me to choose a file. I am not a computer tecno so an struggling with it. Can you give me idiot proof instructions please.

See these instructions: https://support.mozilla.org/en-US/kb/installing-addon-thunderbird

If you read the comments in the ghacks article, the manual method still works in current versions of TB.