How to turn on the light for the back button and apps button?

[aweyrich]

How do you turn on the light for the back button and there close all button at the bottom of the tablet?

 

[PapaGary]

Google is your friend:

https://play.google.com/store/apps/details?id=com.notquiteinsane.galaxybuttonlights2&hl=en_US

 

[dianehelen]

How do you turn on the light for the back button and there close all button at the bottom of the tablet?

That is part of the battery maintenace feature., If you use the middle save power option, those lights stay off. If you choose the full use option, they light up.