I have selected GST as the only sales tax needed, however when I try and add tax to my invoices it adds PST as well. I cannot figure out how to add only GST or if its related to my choice under my settings.

Hi iperkinstree-gma,

Welcome to Community!  Having the sales tax correctly accounted for is key when invoicing your customers.  I'd be glad to assist you with this!

The Sales Tax is configured based on the province that was set up in your work info.    With QuickBooks Self Employed there are two ways you can change this.  If you change sales tax on the Your Work Info page, it doesn't impact draft invoices unless you also change it on them directly.  If you change it directly from the Invoice itself, it will update the current invoice but not in Your Work Info set up.  

For additional information and future reference, follow this link for the QuickBooks Self Employed, Sales Tax Overview.  

Should you require additional assistance with this, please don't hesitate to contact us.  We're here for you!