Just select all of them and then enter the new angle of orientation in the infobox - <-it's usually at the top of your workspaace by default, but I see from how you've organized your space that you don't have it turn on.
No matter, because you can still do it through the Tet Selection settings for all of them at once (with all of them still selected).
The Text orientation angle is the first input box under Text block formatting and you just enter the new angle and all of them will change.
IF you specifically want all of them to rotate by their center, then you have to change their 'Anchor Point' (again, all at once and in the same 'Text Block Formatting' tab.
If you're asking about rotating them all manually (like you can in other programs such as 3ds Max), rather than entering in an angle, that is not possibly in ArchiCAD as far as I know.
You have to know your new angle orientation and enter that number. If it's an arbitrary (non-perpendicular) angle, I would just manually rotate one of them to the angle you want, get the final angle it is as shown and then select the rest and enter that new angle number for the rest of them like I explained above.
