Why have the invoices been changed to show service date and product/service ?

Hello Downendblinds, 

Welcome to the Community page, 

In order to turn this setting on/off is if you go to the customer form styles. 

Cogwheel>custom form sytles> content> click into the second part of invoice> tick or untick the settings you want to see on the invocie>done 

This will now show the invoice as you would like it to be shown in the print preview section of a created invoice.