Just click and drag in the ruler of the text editor.
It seems a little buggy to me as sometimes you can create a new tab between existing tabs and sometimes it just moves the next tab along.
The tabs also seem to be set line by line - not for the entire paragraph when you are adjusting them.
Although once you have the first line set up and then 'Enter' for a new line it will use the tabs of the line above (but still they adjust separately).
Beaten to the punch by Matt.
I hadn't tried selecting all to adjust all lines at once.
Mind you I had never tried to adjust the tabs before either.
One of the forum moderators.
Versions 6.5 to 25
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Dell Precision 3510 - i7 6820HQ @ 2.70GHz, 16GB RAM, AMD FirePro W5130M, Windows 10