On the left-hand menu, scroll down to the settings cog.
Then hit the Video Lib. Settings tab
In there, you can enable/disable your library for all clients.
You can do so on an individual basis as well by going to your client profile then clicking on the blue edit and there. you will be able to turn on/off the exercise library. If turned on, the client will have an extra button in their app to view the entire exercise library.