To change or update UOM in your invoice, You have to edit that product. After editing product you can add invoice to system.
If you are selling online product or multiple UOM then click on "Conversion" button to configure multiple UOM. Example: If you selling sugar (Loose product then you can keep primary unit as kilogram (KG). To configure other UOM Grams (GM) using conversion option.
And now to invoice, the UOM will show automatically. For other invoices, re-select the product and save item list again.
