QUERY <some query name> JOB DISPOSITION - consists of one INPUT process OUTPUT <some output name>

When the user is at the INPUT process of the nested job, and they press F4 to go back, it continues to the OUTPUT. Why does it do this? Can I get it to return to the previous job step?

Yes, you can get it to return to the previous job step. Make sure that your JOB DISPOSITION step is invoked as a Subprocess, not as "related", and make sure that "Separate task" box is not checked. That should do the trick.

There are 3 things that controls if you can or can not return to the previous activity:
1. NEXT CHILD ID - it controls job steps and is shared at the subprocess level. Normally it's set to "+", which means "move forward"
2. Separate task set to "Y"
3. There is a hidden filed on a CHILD file called "Prev Img Ok" - not 100% sure what exactly sets in ON or OFF, but i think it's ON by default now.