When you create a payment or a batch, the default source and destination codes may start at 'General'.
You can change this by following the steps below.
Click Admin, then click Lookups.
Type in Default.
You will see both DefaultDestinationCode and DefaultSourceCode show in the search results on the left hand side.
Scroll down to Lookup Values.
Change the entry to match something that you would usually like to see in your system.