Its ok, inappropriate things will pop up onto your devices sometimes no matter how strong your filter is. Just remember the 3 second rule: If you see something inappropriate on your screen you have 3 seconds to delete it or else it will affect your mind. Don't think about it or stare at it. If you see it, delete it. Once you get used to it it will help a ton.
In general, if you feel like the Yetzer Hara is trying to get you don't fight it, there's no way you can win a fight with him. We call the recovery from our addictions 'battles' but really they should be called 'retreats.' The best way to avoid giving in is by having the mindset of running away from the Aveirah. If you know that if you go on a certain device that you will fall, stay far away from that device. Don't even bother turning it off, just keep it far away from you and go away from it until the urge goes away. It also helps to go into a room where lots of people are, or some public place where you know there's no chance that you'll give in to the Yetzer hara there. If you don't feel like going outside, learning torah, playing video games, reading books, and listening to music are all ways that I have used to get rid of the urge and they really do work as long as the things you're reading, listening to, or playing aren't inappropriate. Going on the Guard Your Eyes website and randomly reading through forums and watching the videos is an even better way to help yourself.
I hope that helps. Good luck on your 'retreats!!!'