How can I change buttons to check boxes?

Hi

I was wondering if I could change buttons to check boxes without affecting the data from surveys I've already collected. 

This is the form. I want them to be able to choose more than one grade level if they teach more than one grade (which I'm realizing they sometimes do...I didn't realize that when I made the form.)

https://secure.jotform.us/thebunkroom/Educators

Thanks

Maria

Sorry...I did see an answer as to how I could easily do the change...however, is that going to affect the data I've already collected?

@Maria

Please download a copy first of the submissions for the form (in Excel or CSV) before changing/editing or deleting the fields. If you edit/delete fields on the form, the submission data for the particular field might be lost.

You can also clone the form first, and edit the cloned form and embed is as the updated form instead. This way you will be able to keep the previous form's data/submissions.

Hope this help. Please inform us if you need further assistance.

Thanks.

Ok thanks! That's what I was thinking...

Will do~