Up to five people may use Diet Sleuth on the same machine. Information is maintained separately for each user.
To create a new user, select Add a New User... from the File menu. You'll be asked to enter the name of the new user. A set of records for that new user will then be created. But at this point Diet Sleuth will still be set up for the previous user. You'll have to quit and re-start to select the new (or another) user.
If there is more than one user, then each time Diet Sleuth starts up, you'll be asked which user should be selected. Select the user's name, and then click on the Select button to continue.