This is a company level feature.
Login to the Company Admin Area
Click on Priorities in the left menu
A grid will show with the current Priorities. These are the priorities that will be used in the app and website when you add an issue.
You can't delete priorities.
To edit the priorities, click on "Edit"
You can change the name (max 10 characters) and the number of days (min 1 day)
To add additional priorities, click "Add Priority"
Enter the name and number of days
Click "Save"