Malware On My Android Phone

I have an Android smartphone which I feel like throwing away right now. Every time I download a video from YouTube, it comes with all manner of viruses, most of which are hard to delete. Now the gadget is too slow. In fact I have to wait for like a minute for it to load all apps. I want to know how I can remove these viruses and how I can protect my phone in the future. Do I have to format it? Thank you.

 

The install a FREE anti-virus/malware APP and make sure it's updated then do a full scan.
Malwarebytes is very good:
https://play.google.com/store/apps/details?id=org.malwarebytes.antimalware&hl=en_GB