How do I set the the media quota and products quota to numbers for different levels?

When using the quota system (screen shot):

https://scontent-b-lax.xx.fbcdn.net/hphotos-prn2/1240411_10151864746351327_1120290221_n.jpg

I would like to be able to set the media quota and the product quota to individual numbers for each level.

However instead they are stuck at the setting: same as posts, and same as pages.

What am I doing wrong that does not allow me to set these settings to a number? Thanks!