I spent some time today figuring out the answers to a few questions I still had about modes. I decided to compile some of the less obvious info. This isn't meant to be comprehensive but should help new owners who are scratching their heads. I have a 2014 SR paired with Android FYI.
Turn on the bike's Bluetooth: kickstand down, key turned on, kill switch off, hold the mode button for 5 seconds.
The smartphone app will tell you that you are changing Eco mode settings. This is not true for 2014. Eco and Sport are not customizable. Any changes you make are for the Custom mode only.
Regenerative braking is disabled when the battery is fully charged. If you make changes to the regen settings, you will not experience anything until the battery depletes a little. You may even notice it is intermittent if you are paying close attention.
To switch modes on the fly, release the throttle and press the mode button. You cannot change modes when traveling faster than 60 mph. The screen will tell you that the mode has been changed but it will not take effect until you slow down and release the throttle.