You can watch the video tutorial, which provides a step-by-step guide through the process.
You can change the title of the invoice email content by following the simple steps below:
Step 1: Open Simple Invoice from your Shopify store’s “Apps” section.
Step 2: Click on “Settings” in the Simple Invoice dashboard.
Step 3: Scroll down to the ‘Sending Options’ section, click on the ‘Mail Subject’ field, and change it according to your requirements.
Step 4: Please click the “Save” button to confirm your changes.