I think this is a pretty simple and perhaps stupid question. I've established log shipping between two SQL Server 2008 servers using the GUI (i.e. the SQL Server Management Studio). It's been running fine -- but now I want to change the number of days the copied files are retained on the secondary server. Is it simply a matter of going back to the GUI and change it there. Is it smart enough just to make that simple change or is the GUI only used to create the initial log shipping configuration?
Yes, you can change this through the GUI.
Connect to the Primary Server using SSMS, right-click your database, and pick properties. On the 'Select a page' pane, pick Transaction Log Shipping.
In the section for Secondary database, you should see your Secondary Server listed. Click the three ellipses to go to the Secondary Database Settings page.
There you should see a section labeled: Delete copied files after
Make your necessary adjustments there, and you're all set.