The Default Checked Option can be enabled on a Custom Field by using the steps below:
1. Navigate to Customization > Lists, Records, & Fields > Entity Fields/Transaction Body Fields > New.
2. Enter a Label for this field.
3. Set the Type = Check Box.
4. Under Applies To subtab, check the record to which this field will be applied.
5. Under Validation & Defaulting subtab, check the Default Checked Option.
6. Click Save.
By design, Default Checked only applies to Standard Forms and not to Custom Forms.
To set the field to be checked by default to Custom forms, perform the following steps:
1. Navigate to Customization > Forms > Entry Forms or Transaction Forms.
2. Click on Edit on your form.
3. Under Screen Fields subtab> locate the field in the specific subtab where it is located and check the Default Checked box.
4. Click Save.