To change the pricing scheme on an order, navigate to Options > Multiple Pricing.
Select from the available pricing schemes (The current scheme is highlighted in yellow)
Notice that the top of the virtual ticket displays the scheme in use, and the prices change accordingly:
You can click on the pricing line to change it back to a different scheme. If you select the default scheme, it will no longer appear on the top of the ticket.
(This feature was added to Thr!ve in version 7.6.0)