We recommend a good disk encryption utility to protect not only your TntConnect database, but your entire computer. If you're on Windows or Mac, you probably have this option built into your operating system.
Mac OS X
Use FileVault, built into the operating system.
Windows
If you're on Windows 7 Ultimate, Windows 8 Pro, or Windows 10 Pro, use BitLocker, built into the operating system.
Both (Open Source)
A well tested and free option that works on both Windows and Mac is VeraCrypt.
Dropbox
If you're concerned about privacy with your files in Dropbox, we'd recommend Boxcryptor to ensure that all your sensitive files are encrypted before they leave your computer and upload to the cloud.
(A great resource to explore additional options is https://www.cloudwards.net/best-truecrypt-alternative-services/)