Thanks for posting to the Community, @shwujen-lam.
Currently, we're unable to customize the payment voucher and expense voucher. I'll take this as feedback and submit it to our product engineers. Please know this feature is implemented based on the number of customers requesting it.
In the meantime, I recommend visiting our Blog site. We share our latest features and product updates here.
Just in case you want to customize your sales forms in QBO and add the info through sales forms, you can refer to these articles:
Please let me know if you have other concerns, and I'll get back to you instantly. Take care!