You've already used the Configure folding slot window to change your number of cores on your cpu so what you can do now is.
From the Configure, then slots option select one of your gpu's and select 'Edit'.
When that window comes up select 'Add'
A small window opens with Name and Value for you to input. There are a view options I'm aware of and probably more I don't.
1. next-unit-percentage (then in the Value line you can put 99 or 100, default is 98) That will change when the next unit gets downloaded to fold.
2. client-type (then in the Value line you can put either 'advanced' or 'beta' (for beta it is advised you be a member of the beta folding team but is not rigidly enforced) beta means that the work units you get are not ready to be released to the public and you may have some problems with them and lose some folding time. advanced means the work unit has passed the beta state and is being tried with a larger folding spectrum, you still may have a problem with some of them, but less likely.