How to iterate through the GalleryItems collection and update

  How to  iterate through the GalleryItems collection and update corresponding records in the 'PO Items' list based on the ID

ClearCollect(
    GalleryItems,
    Glry_Po_Items.AllItems// Replace 'Gallery1' with your gallery control name
);

ForAll(
    GalleryItems,
    Patch(
        'PO Items',
        LookUp('PO Items', ID = ThisItem.ID),
        {
            Title: NewPONumber
        }  
    )
);