[Solved]-Django override_settings won't work for running multiple tests

Well, there is a warning about this very situation.

Warning

The settings file contains some settings that are only consulted
during initialization of Django internals. If you change them with
override_settings, the setting is changed if you access it via the
django.conf.settings module, however, Django’s internals access it
differently. Effectively, using override_settings() or
modify_settings() with these settings is probably not going to do what
you expect it to do.

The first time you run the tests, you are running a specific test case so the override takes effect. The second time you run the test, you are running a whole suite and your specific testcase probably isn’t the first one that’s being run. So the above happens.