Your Whiteboard drawing is up to four times big as your Touchscreens hardware is.
You can display another zoom-button on the right side of the screen by pressing the zoom button longer than two seconds (added at touch-up). To hide the additional zoom-button you just have to press the zoom button for more than two seconds again.
Erase
Clear all
Step by step back
Save drawings and open gallery
Use sticky notes on your Whiteboard drawings
Share drawings by mail
Upload drawings to a Confluence page or JIRA issue