To set up the ability to edit items in the cart, Shopify requires you to manually give the POS Cafe extension permission
Step 1
In your Shopify admin area, go to Sales Channels > Point of Sale > Settings in the left column, then choose POS app in the main window of the screen:
Step 2
On the next screen, click the app icon at the top , then enable POS Cafe:
Make sure to click Save at the top of the screen.
Step 3
You may need to resync your data in the Shopify POS app by following the below steps:
1. Tap on the Connectivity icon.
2. Tap on Shopify.
3. Tap on the Refresh links under Store data.
4. Wait for the sync to complete. Your Shopify POS app is now fully up to date with the latest changes from your Shopify admin.
To edit items in the cart, follow these steps:
Step 1
Tap on a POS Cafe item that has been added to the cart to open it's information pop up:
Step 2
A menu will slide up from beneath the cart. Tap POS Cafe:
Step 3
Edit your item as desired and tap Update Item: