Fields that you see in the standard appointment form can be reordered and new fields can be added to the form if needed. Here is how to do that:
Go to Configuration> Company> Customize>Custom Forms and Fields. Click on the Training Appointment section.
“Standard Training Appointment Form” is the default form that will be presented to fill out when creating a Training appointment
Clicking on the form will open a Form Policy viewer that you can view and clone, but the Standard Training Appointment Form cannot be edited.
If you want to change anything in this form, you can either clone directly from this policy viewer by clicking “...” then selecting Clone:
Or, by creating a new policy:
Creating a Custom Appointment Form allows you to do the following:
Remove optional standard fields, or mark them as required
Reorder fields on the form
Add custom fields
To add a custom field to the form it needs to be created first. This can be done in Configuration> Company>Customize>Custom Forms and Fields>Fields. More information can be found in this article: Creating a custom Field & Field Types Explained



