Thanks for reaching out to us today, @AJCJayne.
I can see how important it is to import custom style for other transactions. Currently, the available is for invoice and estimate. It's a great option that I'm sure our engineers will have to consider adding in the future update.
In the meantime, you can check out for a third-party app that integrates with QuickBooks in importing transaction like Sales Receipts, Purchase Orders, Credit Notes, and Payment Receipts. You can also search through the Apps tab, and then type your keyword in the Search by name or category field. See sample screenshot below.
In case you need help with other customer's tasks, click this link to go to our general customer topics. It contains articles and steps that'll walk you through the process.
Keep me posted if you have questions or concerns about QuickBooks. I'll be happy to answer them for you. Take care and have a wonderful weekend.