In the Account List page you'll see an option on the left panel "Organize business accounts and categories". Make sure, as Cal says, that your Accounts Rcvble shows up as Current Assets. If not set up a new one on this page - you
can even rename it here to include the Biz name. It doesn't sound like you have it set up as a Business account.
As soon as you prepare an invoice, the amount then shows up in Accounts Rcvble until the bill has been paid. When the customer pays, bring up the invoice and click on the option "Receive payment for invoice".
Don't know that you can keep track of two true "businesses" on the same PC though. You might be better installing the Sunset H&B version on another PC for your Animal Rescue unless you never really generated invoices for the Rescue and
really did just keep track of income and expenses.