I have two templates for invoices. When I create an invoice and click on "customise" on the bottom, and then click on my new template nothing happens.... Any advice?

Let me share details on using invoice templates in QuickBooks Online, Contact.

You can preview your template changes by clicking the Print or Preview feature in your invoice, this allows you to see changes in your invoice, including the template applied.

However, if you still can't see any differences in your invoice upon switching templates. Let's perform troubleshooting steps to resolve this matter. 

Start by logging into your QuickBooks Online account using a private or incognito browser. Here are some keyboard shortcuts that you can use:

• Google Chrome: Ctrl + Shift + N
• Safari 11 or newer: ⌘ + Shift + N
• Mozilla Firefox: Ctrl + Shift + P
• Microsoft Edge: Ctrl + Shift + N

After that, check if your invoice has been modified upon changing templates. If it did, clear your browser's cache to vacate cookies blocking the web pages. Removing your cache helps clean up browser cookies that prevent web pages from loading.

Furthermore, visit this blog page to keep up-to-date with the latest features introduced in QBO: New features in QuickBooks.

Keep me posted if you need assistance working with your invoice templates in QuickBooks Online, Contact. I’ll jump right back in to assist further. Have a great day ahead!