Users with the appropriate permission can configure an application which includes enabling and disabling apps, adding lists, making fields required, setting defaults values, changing the numbering system and modifiying lookup lists. To set a default field value:

1. Navigate to the appropriate app
2. Click the Configure button in the app options icon (shown below)

3. Click on the Defaults tab
4. Click the Override radio button (the configuration inherits from the project or area one level about the current project or area you are in. Clicking override allows you to configure the project or area you are currently in without affecting other projects or areas)
5. Select the appropriate field and click the Edit icon 

6. Set the desired default value
7. Click the OK button when done

8. Click the Save button to save your changes