If you include one or more "submit" widgets in the form, the template will use it/them instead of the defaults. So, put something like this in the -form block of ad_form:
{action:text(submit)
{label "Save"}
{value "Save"}
}
/packages/acs-templating/resources/forms/standard.adp tests whether there is a submit in your form (note if @form_properties.has_submit@
near the end) and omits the defaults if there it finds a submit.
You can also modify standard.adp to put in your own defaults as you prefer.