Update Calculation Field on Custom Form Across Multiple Forms

I needed to update the calculation on a custom form, but instead of just adding the new code in I have receive an error code stating " Form Number field is used in a multi-form configuration, if you would like to change this formula you will need to remove this field and replace it with a new one containing the desired calculation".

Form Number is the custom field I wanted to update, but now I have to create a whole new field, add the modified formula, remove this field from every form it's on, and add the new field back where the old was replaced... but b/c I don't want the name of the field to change I have to do this a second time with the correct name.

This is a huge undertaking when every other field updates immediately when an update occurs, not sure why this can't update as well. Even selecting the option of Update Calculation is useless.