Presets are saved in various locations, depending on what type of custom preset it is and which version of Vegas created it.
Since making this FAQ below, some of the information have changed with newer versions of Vegas.
www.moviestudiozen.com/doctor-zen-faq/572-how-do-i-backup-my-custom-presets
OFX presets (like Video FX) are saved automatically to Documents/OFX Presets in Windows.
Event Pan/Crop and
Track Motion custom presets are saved in the Windows Registry.
You need to be very careful when exporting and importing registry keys.
Vegas Pro 17 keys for Event Pan/Crop and Track Motion are saved here.
Type "regedit" in Windows search box and open registry.
Navigate to this folder:
Computer\HKEY_CURRENT_USER\SOFTWARE\Sony Creative Software\VEGAS Pro\17.0\Metrics\Application
I have never personally imported this registry folder into a new install of Windows.
The folder "Application" contains keys for other elements as well - I'm not sure if these can copied into a different computer - technically speaking it should be OK, but I'm just mentioning this out of an abundance of caution.
Right-click
Application folder and select
Export.
Move file onto new computer, then double-click to install.
I would recommend installing the free version of
CCleaner and doing a backup of the Windows Registry on your new computer, before you attempt to import keys from the old computer.
www.ccleaner.com/ccleaner/download 
Remember to turn everything off at least once a week, including your brain, then sit somewhere quiet and just chill out.
