The Lookup button 
is available in most transaction windows, and enables you to search for transactions that have been processed.
The transactions you can look up include:
Each time you look up a transaction, Sage Simply Accounting stores the results of the look up on your computer. You can clear this lookup data to make more room on your computer.
The Search window is the primary tool used for looking up records and transactions. There are several ways to open the Search window, and each way affects what you can search for. If you open it from:
When the Search window is opened from the Home window, you can also take advantage of the options on the Advanced search tab.
Bypass Search Field. Allows you to skip the Search box and go directly to the records listed at the bottom of the window to begin your search.
Search for a record or transaction