You can watch the video tutorial, which provides a step-by-step guide through the process.
You can convert a draft order into a quote by following the simple steps below:
Step 1: Open Simple Invoice from your Shopify store’s “Apps” section.
Step 2: Click on the ‘Drafts’ on the Simple Invoice dashboard, select the order you wish to convert, click on the ‘Convert’ button, and select the ‘Quote’ option.