If you have modified a drill it will affect the test that contains the drill. After releasing, the test is 'outdated'. This means that the test still contains the previous version of the drill.
By updating the drill version with the test you can make sure that you show the latest content in the test to the participant. Keep in mind that your test is different if such large changes have been made.
Updating the test
If you want to update, go to "My content". Here you look for the button. Select the test and use the option, "manage drills".
Now you will see all drills on which the test is based. For each drill, you can now indicate if you want to update the drill version.
If you have deleted questions in the drill and/or changed tags so that the test no longer contains enough questions, you cannot update the version.