The "Social Lender" and "Balanced ROI" are just templates that you can use to set the note selection parameters. If you click one of these it resets your filter and assigns the predefined filters for that selection. You can see your parameters at the bottom of the bottom of the summary page. For example, here are the parameters set for "Social Lender":
model >= 85 & inqLast6Mths <= 2 & installmentIncomeRatio <= 15 & delinq2Yrs <= 0 & pubRec <= 0 & intRate >= 14 & grade %in% c("B", "C", "D", "E")
Now, if you go to these parameters on the left you will see that they are set and you can change them for your particular note selection criteria. Again, this is just a quick way of setting the filter if you have absolutely no idea of what parameters you want. I recommend adjusting to suit your needs.
Since this filter has "model >= 85" as part of the selection filter, it will select only notes that have a model score above or equal to 85. PLS assigns a probability score to each note that predicts the likelihood of the note to be fully paid. The higher the score, the more likely the model believes the note will be paid. Of course you dont have to use the model in your note selection criteria. It is there to help but not required.
When I have time I will be creating a document that details the model and the process of how it was built. Its a gradient boosted model which uses an ensemble of decision trees.
If you want more notes to be purchased, you will need to loosen your filter selection. I am not sure what your filter looks like but it seems to be selective and perhaps a bit too tight. Play with your parameters and review the summary page to see historically what percentage of notes match your criteria.
Maximum notes per order is the max number of notes that can be placed per order. It is a safety measure to ensure that if your filter is not set correct or too loose you don't buy too many notes.
The max percent is another saftey measure (probably a bit too paranoid) that will cancel the order if it is above the max percent of total notes. So, if you have it set to 50% and there are 100 total notes that can be ordered, and your filter wants to order 50 or more, the order will be cancelled. I tried to code in safety measures especially for people who don't understand how to use the software. I have heard of other tools completely buying all available notes because of a bad filter and wanted to avoid this potential problem.