For e.g
If the thread URL was
https://www.b4x.com/android/forum/threads/how-to-set-tooltip-for-a-textfield.123227/
When you try to open the old URL, it will automatically redirected to the latest URL
https://www.b4x.com/android/forum/threads/resolved-how-to-set-tooltip-for-a-textfield.123227/
I don't understand why you say it is not good for SEO. I think editing/adding "RESOLVED" to the title is very useful for the forum.