Worked out how to do this… I had collaboration switched on so please ignore

Hi can any one help? I’ve created a formula field that looks at a set of drop down boxes that gives a score of 1 to 3 the formula then gives me the total value of all the drop down boxes.  I then use the same form and create a copy to save me having to recreate the entire document from scratch.  However when I do this the formula doesn’t work any more on the copied document and I have to recreate all the drop down boxes again for it to work. Any one know a way around this or why it’s doing this?