Opening balance for vendors

Opening balance for vendors

I'm trying to migrate to Zoho Books. I have a vendor with an existing balance (in credit, due to regular payments on account). The documentation tells me to find the "Opening Balance" field under "Other Details", but it isn't there. Under "Other Details" I can see VAT Treatment, VAT Number, Currency, Payment Terms, Facebook and Twitter, but no opening balance.

How can I enter the opening balance for a vendor?