New to using an online platform like this and can't find a easy answer anywhere. When adding my customers there is a box saying 'taxable'. Do I need to click this?

Hi info-bellasbouti, welcome to the Community

The taxable box allows you to set a default tax rate (VAT code) for your customers. You can leave this option unchecked if you don't charge VAT.

For further help, you can visit our getting started with QuickBooks guides. We're just a post away if you have further questions.