"Templates which may be overridden per app or model Not every template in contrib/admin/templates/admin may be overridden per app or per model. The following can:
app_index.html
change_form.html
change_list.html
delete_confirmation.html
object_history.html
For those templates that cannot be overridden in this way, you may still override them for your entire project. Just place the new version in your templates/admin directory. This is particularly useful to create custom 404 and 500 pages."
Where must I put the submit_line.html file in order to change it? I have got my TEMPLATE DIRS set up for multiple paths. This is what my file structure looks like:
app/
templates/
app/
project_name/
templates/
admin/
project_name/
app/