Options, Undo and Search
Options button:
On the upper left corner next to the 
Tools menu there is the Options Button. If there is no object selected, you are able to adjust the Graphics View by using this button.
It is possible to 
Show All Objects and get back to the 
Default View. In addition you can switch the 
axes on/off, as well as change the type of 
grid that is shown.
If an object is selected, after clicking on the Options Button you can change the Object Properties. You can modify the object's’ color, thickness and style.
Note: the properties are different depending on the type of object.
Undo button:
In the upper right corner appears the Undo button after doing some activities. You can use it if you want to undo a construction or a movement.
Note: The Undo button appears also in the Toolbar.
Search button:
On the upper right corner, between the Undo button and the 
Menu button, you can find the Search button. It allows you to search for a GeoGebra Material from GeoGebra Tube. After selecting one, the GeoGebra App opens it and adapts the content to your phone. 