My client wants the ability for customers to purchase more than one item, in this case, posters. Some people may be buying posters to resell in their stores so they may want 10 posters. How do I do this? I just found out that there is a button to hit to let customer chose quantities. Is there not a global way to do this? I have over 400 posters...

Hi Dan,
You have to set that amount for each. Export your shop to CSV then use a spreadsheet program to change the options quickly. Make sure you set one item the way you want before you export so you get the format correct.