The 'New Connections Defaults' options window ( illustration) is where you set the options for a new connection. These options are applied to each new connection you create. You can modify any connections options by using the 'Connect to' window (upon creation) or connection properties (after creation).
There is no way to change the properties for all existing connections at the same time.
New connection defaults window
You can configure the following options:
If this option is checked, the port for all new connections will be set to 4899.
You can set a custom port number here.