How to link a sales receipt to the default template? It does not pick up the right one and cannot see 'customise' at the bottom.

Hello Katerina166, 

Welcome to the Community page, 

Can you try zooming the page out as the customise button should be there on the bottom middle of the page. Try clearing your cache and cookies to see if that resolves the customise button not showing. Let us know how you get on.