re : I want to add a new tag but when I do it's being added before the last

What method are you using ? Are you creating a Tag in 'Settings > General > Tags section ? Or via Menu Bar - 'Message' > 'Tag' > 'New Tag' Or right click on email and choose 'Tags' > 'New Tag'

Please check - does issue occur no matter what method you use ?

How many tags have you got in the List? Post an image showing all the Tags in List.

re :The answers I found for this didn't work for me. What answers are you talking about ?

What version of Thunderbird are you using ? Help > About Thunderbird has this info. What OS are you using ? eg: Windows 10, MAC, Linux etc

Both methods you describe yield the same result. There doesn't seem to be a way to change the order of existing tags in TB. There are various conversations on the web on this topic but no real solution. I tried the one described on tis page https://superuser.com/questions/1543390/how-do-i-reorder-tags-in-thunderbird but it removed all my applied tags so this is not the solution I was looking for.

I change the order of tags this way:

- create the tag(s)

- go to TB menu > Settings > General

- scroll all the way down > click the 'Config editor' button

- accept risk and proceed

- search for: tags

In the list that appears, I rename the tag and color entries alphabetically, in the order I want the tags. e.g.,

mailnews.tags.$label1.color #CC0000 mailnews.tags.$label1.tag Important

mailnews.tags.financial.color #009900 mailnews.tags.financial.tag Financial

mailnews.tags.nappointment.color #800080 mailnews.tags.nappointment.tag Appointment

mailnews.tags.scoupon.color #996633 mailnews.tags.scoupon.tag Coupon

mailnews.tags.to_do.color #2d2dff mailnews.tags.to_do.tag