hacking my tablet

[Yezz Dk]

Need help have 2 tablets android, today it was like someone had taking control over them opening my mail and was typing ... i looked and it. Was like someone was using my tablet without my notice ....when i looked at the sceen it was typing and opening this quite scarry .....is it hacking virus or any ideers please help have installed 3 virus programs but nothing to find when iscan