If you have a dress in layaway and have decided you want a different dress at david's bridal can you apply your payment to the new dress you want?

Although it seems like a reasonable request, you will need to check with the store about their policies. Their website says that there will be a 10% forfeiture fee for any layaway that is returned to stock due to cancellation or non-payment. I don't know if an exchange would be counted as a return to stock, so talk to their Layaway department.