https://play.google.com/store/apps/details?id=com.loadlynx_jp.vollynx.free&hl=en
This app should work to stop the ads from turning on the sound forcefully. Make sure to set up all of the volume options to zero, and then click on the lock so the volume is locked, which doesn't let Yoolotto change the volume.
Hope this helps!
EDIT: You do not need root to use this app! I personally think this is the easiest way to turn off the sound permanently.
I use a auto cache cleaner from the app store - https://play.google.com/store/apps/details?id=com.jrummy.cache.cleaner it's compatible with ALL of my devices and it's under 1MB including data - I schedule it to run every hour!
Got this in my email:
Important YooLotto Service Alert From Our Advertisers:
Our advertisers have informed us that all customers need to upgrade to the latest version of YooLotto on their Android phone immediately.
Please note: you need to upgrade to version 7.29 immediately so you can continue earning points. You will not be able to watch and earn on earlier versions.
If you have not done so already upgrade now: https://play.google.com/store/apps/details?id=com.yoolotto.android&hl=en
Note: this is specific to Android phones only.
Thank you, The YooLotto Customer Support Team
Volume Locker was suggested to me in this subreddit, and it works at keeping the volume locked at what you set it at, and it does not require root.
https://play.google.com/store/apps/details?id=com.loadlynx_jp.vollynx.free&hl=en
This tablet is pretty popular https://www.amazon.com/Amazon-Fire-7-Inch-Tablet-8GB/dp/B00TSUGXKE/ref=sr_1_2?ie=UTF8&qid=1474835883&sr=8-2&keywords=fire+tablet. I had a lot of these on Yoolotto before the update made the tablets not work anymore.