As a buyer, you can change an existing cash price by completing the following steps:
Deactivate the Existing Cash Price
To deactivate the existing cash price, you will first need to navigate to the prices screen. To do this, simply click on the prices tab in the navigation menu, or click here. You will now see a list of the existing cash prices that you have created. You will also see a red 'Deactivate' button adjacent to each price. Click on the deactivate button that corresponds to the price you wish to deactivate.
Create New Cash Price
Following the above, simply go through the same process that you would to create a new cash price. If you have forgotten how to create a new cash price, you can refresh your memory here.