Hi there nik-lacroix-gmai,
QuickBooks Self-Employed keeps things simple when it comes to entering data for your business, and luckily, making changes is also a fairly simple process. I'd be happy to go over this with you so you can correct the date on the invoice.
The program's Invoices tab is where you can manage these transactions, so I recommend starting there. For the invoices listed there, there will be a few options in the Action column depending on the status of the invoice. For instance, if it's already been paid, it'll show View; if you're waiting for a payment, it'll show Mark as paid; if you haven't sent it yet, it shows Send invoice. Apart from those options, the drop-down arrow in the Action column also gives you more to choose from, including Edit. Clicking that option will bring the invoice up for you so you can make whatever changes needed, including changing the date.
Once you make the change, hit Send reminder to make sure the program saves this information again. To avoid confusing your customer, feel free to include a note in the Message field about the correction you made or use the Email message field on the next screen after hitting Send reminder. Once you're good to go with that, click Send.
One thing to keep in mind about QuickBooks Self-Employed is that in order for an invoice to save, it needs to be sent, so making sure it's sent is key here. Here's our article about this feature for your reference: Create invoices in QuickBooks Self-Employed
Give that a shot and feel free to let me know if you have more questions. Take care.
