Why can i not use my master invoice when creating a invoice to customer?
I got your back, and I got questions to help us get to the bottom of this.
When you say you can't use it, do you mean you can't select it, or you can but your invoice doesn't show like how a Master (Standard) template does?
If you can't select the template when you click on Customise and choose Standard on the Invoice page, you can switch to a private browser. Then, log in to QuickBooks, create an invoice and choose the template. If you can select it, go back to your regular browser and clear your browser's cache. If it's the same, you can try other browsers.
On the other hand, if you're able to select it but your invoice doesn't show like how the Master template does, you can do the following:
Check your Standard template to see if it was changed.
If you have another template which is marked as default, remove it as default first and try creating an invoice using the Master template. Then, switch it back later.