This form is only modifiable by changing the code outside of a setting or two I think exists in Globals Admin. As Shameem states, that is an important part of the new versions that should not be messed with too much, but since you are running 3.2.0, you MIGHT consider upgrading a few versions (all the way to 4.1 might be nice) and see if THAT takes care of your issue first. It's a lot easier to get help with a newer version (hey it IS free).
I am not sure where the file was in 3.2, but now some of the file names associated with "issues" are add_edit_issue.php, left_nav_issues_ajax.php, link_issue_to_encounter.php, and ippf_isues.inc.php...and naturally all their include files. They are in various locations, but you can search them out with those file names.
Mind if we ask what your goal is? Maybe we can help better.
OEMR Board Member