Navigate the the location below in your registry and make the corresponding change.

Create or edit the existing DWORD value (string value for Windows 98) named "DnsServerPort" and set it to the desired port address. 

Restart Windows. 

Key:[HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\MSTCP]
Value Name: DnsServerPort
Data Type: REG_DWORD
Data:Port Number (Default = 53)