How to register additional setting field to umbraco form setting screen. Please refer image for a clear idea
There are so many tutorials/Documentation about adding additional attribute to field type EX: https://docs.umbraco.com/umbraco-forms/developer/extending/adding-a-fieldtype but can not find any documentation about adding custom setting field to umbraco form setting window. I believe some expert can help on this requirement.
I don't think this is an option, to be honest. You should, however, be able to style your submit button if you use the "Form CSS class" instead and use something like
.my-forms-class input[type=submit] { color: red };
to target the submit button?Otherwise, you could try and make a feature request here: https://github.com/umbraco/Umbraco.Forms.Issues/issues/