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

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

3. Click on the Fields tab
4. Click the Override radio button (the configuration inherits from the project or area one level above 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. Click the checkbox in the Required column next the field you want to make required
6. Click the Save button