If you go to Setup>Custom Forms and click the "Fields" tab, you can see all your fields. If you create a new view and add a "Forms" column, you can see all the forms the field is used on:
descriptionkey=form.plural
linkedname=direct
namekey=customfieldforms
textmode=true
tile.name=component.custom.field.forms
valuefield=customfieldforms
valueformat=HTML
viewalias=customfieldforms