Having trouble to configure the Logitech mouse button? Well, it happened to myself as well. I bought a Logitech m950t performance mouse and eager to try it. The mouse itself I found comfortable to use and it is big enough to cover on my palm. Unfortunately, you will not find any software comes with the box. The good news is, most operating system like Windows will automatically detect the mouse when you plugin in the Bluetooth USB connector. Unfortunately the built in mouse interface in Windows does not give any advanced button configuration for the mouse. Therefore you will need the software supplied by Logitech directly.
Searching on the google does not give any quick answer easily. Even on the Logitech site, I found a bit trouble searching the appropriate software for the mouse. So to save your time, I have summarized the quick link for you to download and you can just easily install it and configure your mouse button. The software name you need is call SetPoint. This software lets you customize the buttons for Logitech mouse and keyboard.
http://support.logitech.com/en_us/downloads
Once the file has been downloaded, simply double click and install the software. Once installation is completed, you can easily assign commands to your mouse button. The software automatically detect the type of your mouse and display the image of it.