To add yourself as a owner of a group, go to the group and select:
  1. Roster
  2. Manage
  3. Click Owner next to your name
Now go back to the Settings of the school form >
  1. Click Recipients
  2. Add
The Group dropdown will now display the group you just added yourself as an owner to.

Alternatively, if the Group is a Community Group using a Smart List, being the owner is not relevant.
Instead, you must be included as a natural result of the Smart List criteria.
This can be accomplished by adding yourself into the criteria by name, as with this example:

Additionally, if you are added to the group via either a Smart Group or added as an owner of the group you must have Group Page Access to be able to view the group before it can be seen in the Groups dropdown of a school form. In order to give yourself access to the group:
  1. Navigate to Core > Security > Group Page Access
  2. Click on the Tab of the group type you wish to grant access (Such as Communities)
  3. If you are not already granted access to the group click "Add Access"
  4. Include the Role that is granting you access to the group
  5. Click "Add Access"