In order to get the latest version of Betternet, you first need to download the latest version of Betternet. If you're unsure how to do that, please read the article How do I download Betternet on Windows?
With the newest version of Betternet downloaded, launch the installer. You will be presented with two options: Uninstall, and Repair. Select Uninstall
Follow the instructions in the application. It can take about a minute for the application to get uninstalled. Eventually, you will be presented with a Finish screen. Click on Finish.
With the application now uninstalled, launch the installer that you downloaded.
This time, click the Install button and follow the instructions in the application.
Betternet will proceed with the installation. When completed, you will be shown a screen that the installation was successful. Click on Done.
You will now be using the latest version of Betternet for your computer.