Saving Changes Is Not Permitted On SQL Server 2008 Management Studio. How To Solve?

Saving changes is not permitted occurs when doing alter table (table structure is changed):

1. Change data type on existing columns
2. Or change allow nulls on existing columns

 
To allow you to save changes after you alter table, do disable prevent changes:
 

1. Open Microsoft SQL Server Management Studio 2008
2. Click Tools menu options, then click Options 
3. Select Designers 
4. Uncheck "prevent saving changes that require table re-creation" option
5. Click OK
6. Try to alter your table
7. Your changes will performed as desired