I've never used ID's new form features, so I don't know if yo can set that property for a checkbox directly in ID, but you should be able to to do this in Acrobat. As I recall, all the check boxes need to have the same control name.
That said, the select-one-only behavior is usually associated with Radio Buttons, not checkboxes.
Thanks Peter, that may sort the issue anyway, never thought of using radio buttons instead. If there is a way to change the appearance of the radio button to view as a tick, then the issue would be solved, however I am sure a circle would suffice.
Thanks for your quick help.
Thank you for placing my post in the correct place.
Just found a possible solution if anybody else gets stuck on this.
Saved as Interactive PDF using the radio buttons, then opened in Acrobat and in the properties of the radio button, then under 'options' changed the 'button style' to 'check' and that seemed to work.
This is accomplished by simply naming the check boxes the same name, which creates an array in which only one can be selected at the same time. In your Buttons and Forms control panel, set two or more check boxes to have the same name, the Button Value can of course be different.