Test strips are notoriously inaccurate. It is recommended to get the liquid test kits. Plus, you need a reading on ammonia, which is the first toxin to rise and harm your fish.
But going by your strips, I'd say tank one needs a large water change NOW. You don't ever want nitrites as high as 1 ppm, and tank 1 looks to be approaching 5 ppm. I'd also do a wc in tank 3 due to nitrites not being at zero, and looks to be above 0.5 ppm
I'd do those changes immediately, and then go buy the liquid kit.