Change category (Folder) for many mails in bulk not one by one

I accidentally move a helluva lot of mail from main folder (A) to Sub Folder  (B), really stupid of me. 

In order to explain in more detail I have attached a screen with info from number 1 to 2. You will have to click on the image so it opens in a new tab and much larger.

Thank you from a sunny South Afrika (Suid Afrika)

Thank you (Baie Dankie)

Note I am a user

Do you want to move them back to original folder   ?  or Change the category only ?

First run emclient backup in case things go wrong.    Menu - File - Backup  so you can restore back to square one. note A RESTORE does not restore the theme especially any custom one so make sure you have a copy of it saved away.

Move them back to original folder :
Select the folder it went to
Select the first email item and hold down the shift key and hold it down
    Move to the last item and select the last one all should be highlighted   now release the shift key
Select (right click) move to folder and point it back to where it should be.
It will take a while.  Get a cup of tea or coffee.

Change category in mass:
Same steps as the move   but look for  the category option