When I have more than 1 box selection how can I make it only choose one or the other?

I am not sure if I have understood your question correctly. Do you mean to say that you want your users to be able to select only one option from the list of options?

I would suggest you to please add "Single Choice" question in your form and that should solve your problem. Please check the screenshot below:

Hope this helps.

Do try it out and get back to us if you have any questions.

Hi yes single option works now however if i have two questions linked to each other so the 1st is answered no then the 2nd answered yes, if then i change the 1st answer on the form to yes the 2nd question disappears but the rest of the form doesn't.
So what i need it to do is when the 1st button is pressed, to reset the 2nd to not opted but show the options .
I hope this makes sense?
Steve Perryman | Glory
Supervisory Engineer Booths Park, 5 Booths Park, Chelford Road, Knutsford, Cheshire WA16 8GS UKPhone: +44 1565 654662 fax: +44 1565 658657 mobile: +447852717230
steve.perryman@glory-global.com
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Generally, in order to clear the values of hidden fields automatically, there is a setting for this: 

It looks like you have already enabled it for your form PM Finder. Does the problem still persist?