How to stop redstone flashing in minecraft?

I play minecraft PE and recently started using redstone, so I decided to use it for the lights in my building that was already built, using a lever to turn them on and off. I have tunnels going underneath the building carrying the redstone and the repeaters. For one set of lights, I have four lights operated from the one lever, I basically had two and two and joined them together. But when they are turned off, two of them flash every so often, I've tried everything to stop it but it's not working. I've heard of having a 3 block height above the redstone, which I did, but it didn't help. Another set of four lights also acted funny, two of them flashed while switched on, but I fixed that by just adjusting a repeater, I did that with the other one but it didn't work.