By default the upload button name is "Upload file" You can change it to any name you need. to change the name very simple for a product just go to the "Products" menu and select the product name
After clicking on the label button, you will see a box labeled "upload file." Simply replace the existing text with any text and don't forget to save it.
For the global setting, navigate to the "Settings" menu and modify the box name from "Upload File" to your preferred label.