I think I've figured this out - mostly (for anyone still searching). If you follow the initial process suggested; Customer, Receive Payments (select customer you are clearing out). Then select the icon at the top that says "look up Customer/Invoice" and you will then need to "Search By" the invoice AMOUNT (or rather the JE amount). < That's the unfortunate part - I've only found a way to 'write off' the offsetting amounts that are exact equals. So, if you have a JE for 1,000 and another, offsetting, JE for (1,000), you can clear those out against each other. However if you have a JE of 500 and another JE for 500, and then an offsetting (1,000), I can't seem to figure out how to clear those against each other.

Anyway, once you have found the "amount", you'll select "Use selected customer or transactions". For me, it then pulled in ALL JE's for that customer, and that's when you go into "Discounts And Credits". Selecting that icon will automatically pull up the JE offsetting amounts (and it actually selects the exact offsetting amount), and you just hit Done. From there, you can select the next line item listed (which for me is another JE), and use the "Discounts and Credits" option again.

I tried attaching screenshots, but it won't let me - sorry y'all! Hope this is at least kind of helpful!!