You can edit your User Defined Fields (UDF) so that a value must be selected in the field before you are allowed to save. For example, if you have a User Defined Field applied to Transactions and you make the field required, you will have to fill out that field before being able to enter any new transactions or update existing ones.
1. Click Management in the menu bar 2. Click User Defined Fields, in the Database Configuration tile 3. Click the Category your field is stored under 4. Click the name of your field 5. Click Step 3: Field Attributes 6. Check the box next to 'Would you like this field to be required?' 7. Click Save and Finish