Anyone know what impact this setting has during flight? I tried moving the slider all the way to the left and later to the right and I couldn't see any change in the live video feed. Will this have an affect on range since less bandwidth would be used for video?

Image transmission code rate will affect the range. If you set a higher code rate you will get less range and if you set lower code rate you will get a wider range accordingly.
Besides, it will also affect the transmission quality to some extent.

Where is that menu i use Android phone..??

i like how dji thor addresses this like its an intended feature of the spark... it isnt as of right now on current variants of the firmware.  unfortunately it is just a software glitch that occasionally rears its head.  changing it makes no impact right now, it is possible very easily to activate the feature and get it to work, but doing so requires some tinkering with spark's update file.   

Besides, it seems like you connect the drone with OTG cable because it shows the HD icon which should be Wi-Fi settings.
The connection between the Spark RC and the mobile device via OTG cable has not been fully tested, so I would suggest that you use it with caution.