Add Invoices related list to the Opportunity Page Layout

To add the Invoices related list to the Opportunity Page, enter Setup in your Salesforce Instance and please follow the steps below:

Step 1 – Under Build navigate to Customize -> Opportunities and select Page Layouts.

Step 2 – Select Edit next to Opportunity Layout.

Step 3 – Select Related Lists and drag Invoices down to the Related Lists section.

Step 4 – Select Save to action the changes to the Opportunity Page.