The button decrease the volume.
The button increase the volume,
Settings Menu
The settings menu allows you to adjust Tablet system configuration.
To change settings:
Wi-Fi - Connect to /disconnect from wireless networks, view connection status
Data usage - Enable / disable mobile data, view current usage, set mobile data limit (note:
this function is available only on devices supplied with 3G card)
Sound - Change volume, touch sound, screen lock sounds etc
Display - Change brightness, wallpaper, sleep settings, font size etc
Storage - Manage NAND and Micro SD card, view available capacity etc
Battery - See battery status and powered-on time
Apps - Manage applications, running services etc
Accounts & sync - Switch synchronization on /off, manage accounts etc
Location services - Change approximate location detection, improve search results
Security - Change screen lock type, encryption, password, credential storage etc
Language & input Select language, add to the dictionary, edit on-screen keyboard settings,
vocal search, etc
Backup & reset - Backup & restore data, perform factory reset, etc
Date & time - Set date, time zone, time, clock format etc