Disabled mandatory checkbox of custom fields

Upon customizing a custom transaction form, the Mandatory checkbox of custom fields is disabled or grayed out. This happens when the custom field is set as mandatory on the Custom Transaction Body Field Settings. 

 
Solution 

1. Navigate to Customization > Lists, Records, & Fields > Transaction Body Fields 

2. Click Custom Transaction Body Field 

3. Click Validation & Defaulting 

• Mandatory: Remove Checkmark 

4. Click Save 

 
After saving, the Mandatory checkbox of the field on the Custom Transaction Form should not be grayed out anymore and users can now edit or change the settings.