To change a product SKU from either an upper case or lower case.
- Retail POS for Mac or PC
- Navigate to Catalog -> Products
- Click Export List...
- Open your CSV
- Read this guide before making any edits
- Edit the SKU column to include the uppercase or lowercase letter
- Save the CSV
- Navigate back to Catalog -> Products
- Click Import
- Drag or browse for the CSV you saved
- Wait for the CSV tool to load your updates