In SQL Server Management Studio Object Explorer - How to increase Font Size?
From the tool --> Options --> Fonts & Colors we can change fonts for many windows. T
This is a known issue, and will not be fixed at this time.
http://connect.microsoft.com/SQLServer/feedback/details/691432/ssms-should-be-able-to-set-font-size-for-object-explorer-registered-servers-and-properties