Complete the following steps:
- Log into your cpanel, and go to Products > View All Products in the menu.
- Click on "pricing" in the navigation bar.
- In the "Pricing & Tax" section, you can see "min" and "max" fields, which is where you enter your minimum or maximum quantities for the product. For example you might want customers to buy a minimum of 5 (min) of this product in a single sale, but no more than 10 (max).
Min/max quantities can also vary depending on the user group. To define these, click on the "Show all" button to reveal the fields for all user groups.