It made me feel good that the current reigning world champion is/was also confused about roll centers and how to adjust them.

http://jtprc.com/2013/12/29/setup-tip-roll-center/

In a nutshell:

Lowering the inner link = less roll
Raising the inner link = more roll
Lowering the outer link = more roll
Raising the outer link = less roll
A lower “roll center” rolls more
A higher “roll center” rolls less