In order to have a clear idea about Invoice settings, Go through Purchase Order Settings.
Apart from the fields that are similar to the ones in purchase orders the remaining fields that exist in Invoice settings are discussed below,
Company name on Invoice: The name of your company which is displayed on your invoice page.
Company address: The Address of your company
Authorized person: The company Authorized person name.
Authorized person Designation: Designation of your Authorized person.
Authorized person signature: Authorized person signature.
Invoice Logo: Invoice logo which is displayed on the invoice page.
Add Invoice Payments to Income: If Yes, then the amount will be added to Incomes.
Sale Agent: If Yes, the Sale agent name is shown on Invoice.
Default Category: While making a payment, the category should be shown default.
Default Recurring Invoice Category: While making a payment, the Recurring Invoice category should be shown default.