You are able to upload your own signature for receipt.
1. Go for "Print" after you choose the invoice u want it to be printed to receipt.
2. Click "Customize"
3. Select "Footer" and you will see the image as below
4. Choose the side for signature and upload the image.
You can also change to key word, example -- "Prepared by" to "Bryan Soong"
5. After save, you can view the signature you upload image in the invoice.