Paisley.
For Invoices.
Select the "Reports" tab (from Accounts, Home, Sales, Purchases, Banking, Reports, Suite).
Select the Orange "Invoices Report" Box.
View the report.
There are two options at the top of the Invoices Report - (Report and Help)
Select Report then use the Save as CSV drop down.
I am using a v4.92 demo but maybe this will work on earlier versions as well - good luck.