You can change your password on the Settings screen of the Samsung Portable SSD software as follows:
Click the Set button on the Main screen, move to the Settings screen, click the CHANGE button, enter a new password, and save it.
When setting a password, you may include spaces in your password on a device running the Mac OS, but will not be able to save it; on devices running the Windows OS, you cannot include spaces in your password. You can set a password on PCs running the Windows OS or Mac OS.