So apparently my brain is block some how... I do what is down below then teleport or walk away a bit then do /portal settarget Portal_IDNo 7 for instance.
nothing happens ever!! 

I have been trying to do this since the plugin was a youngn.
I was successful once upon a time.... maybe I should of recorded it. 🙄
First off do you need to make new portal around you when you do the settarget? that still does not work. Please advise.... ( I love that phase)
I do it as written still....
use /portal select and select an area no smaller than 1x1x3 (length x width x height) from the floor
use /portal create Name_of_your_portal to create the portal
go and stand in the place you want your portal to teleport to and type /portal settarget Portal_IDNo (you will get a message with the ID number of your portal when you created it, else you can use /portal list or /portal show to see it)
your portal is fully functional, hurrah! 