The B2B:Wholesale app is designed to show the wholesale form or wholesale page for products to give the possibility to add products in bulk to the cart. But it doesn't provide an option to set different prices for wholesale and retail, sorry. The app just displays prices set for products in the Products section of your Store Admin.
As a workaround, you may duplicate the required products and apply the wholesale pricing in your Store's backend and then use these products with our wholesale Shopify app.