(1) Make sure that the latest version of iOS is installed on iPhone, iPad or iPod touch.
(2) To use the latest functions of Memo, please make sure that Memo is set for use with iCloud or stored on the device. Many functions of Memo cannot be used with other email providers.
(3) If there is graffiti in the memo, make sure that the latest functions have been updated.
Extended Materials With Memo, you can draw pictures, create lists, scan and sign documents, and add attachments such as photos, videos or web links.
The search function in iOS 13 can even identify the contents of the pictures in the memo. For example, if you search for "Bicycle", the search function will display all images containing bicycles. In addition, the search function can also find specific text in scanned documents, such as receipts or bills.
You can use iCloud to update notes on all devices. To set up a memo for use with iCloud. You will see the memo on all Apple devices that log in with the same Apple ID.
References:
Apple official website-Using Memos on iPhone