Tube Toolbox maintains your lists, messages, sending history, etc. in a single database file on your computer. If you want to copy all of your data between computers, you simply need to copy this one file back and forth. Moving this data file around from computer to computer means that each computer will be reading and writing from the same set of data. This is the best way to avoid sending a message or comment to the same person twice when sending from multiple computers. The location of that file depends on what version of Windows you are running.
Windows XP
> C:\Documents and Settings\All Users\Application Data\Sincell\Tube Toolbox\TubeToolboxData.sdf.
Windows 7/Vista 64-Bit
> C:\ProgramData\Sincell\Tube Toolbox\TubeToolboxData.sdf
Note: "C:\ProgramData" is a hidden folder on your computer, so you need to manually type it in, or just paste this into Windows Explorer:C:\ProgramData\Sincell\Tube Toolbox\. ProgramData is not the same thing as Program Files.
Still having trouble finding the folder? Launch Tube Toolbox and click on the Folder icon on the log-in screen. 