This form is opened when you press the Change button on the Project Updates form for a symbol that is newer than the corresponding one in the database.
Update Symbol
Update 'Symbol' in the database
Switch this option on to update the database version of the symbol with the imported one.
Ok
Press this button to continue with the update.
View
Press this button to view the two versions of the symbol.
This different version of the form is opened when you press the Change button on the Project Updates form for a symbol that is not in the database. There are three possible choices from the Action button, each which displays a slightly different form.
Update Symbol
The symbol will be converted to a block with the same name as the symbol.
Update Symbol
Use the selector 
button to choose a different symbol from the database. The imported symbol will be replaced with this one.
Update symbol
Save Symbol As...
Press this button to open the Save Symbol As form, and specify the required details.
On each of these forms you can press the View button to display the symbol.
The Ok button will become active once the necessary information has been supplied.