The default behaviour of Alt-Z in a fresh DataCAD install is to go to the zoom (display scale) menu. These shortcuts are stored in the dcadwin.mcr file in DataCAD's Support Files folder and I'm guessing that you copied in the default version of that file when you reinstalled DataCAD. You must have edited this file (or copied in a custom version) some time in the past to get the Edit Text functionality that you are used to.
If you have a backup of your old dcadwin.mcr file then copying that over the default file should get all your custom shortcuts back.
If you don't have a backup then you will need to edit the dcadwin.mcr file to adjust the entry for Alt-Z. Josh Huggins has previously posted an example of the change that needs to be made