When I try to drag parts from the toolbox, they appear as "read only" and I can't change their features. I did a re-install, but didn't fix the issue. What I am trying to do is make a custom part based on a standard spur gear. But I can't even generate the right spur gear that I want to use as a base. I'm using SW 2016 Prof on a freestanding, single user pc running Win10.
Start a new assembly and then insert the desired toolbox part OR right click on a part and select create part
Now you should see the option to pick the desired values.