Can't use all commands on a Minecraft PE world

I have copied a survival world that had achievements on it to make a creative world because I liked the seed. I built a little village there and I now want to put in some command blocks. However, even though cheats are activated on this world, I can't use the /give command to give myself a command block. I am on the latest PE version, 1.9, and haven't had problems with commands before. Is there anything I can do?

Solution 1:

In the world settings on the server menu before you join and find "Cheats" the first tick there is "Activate Cheats" make sure that is ticked on. When you are in game tap the pause button and click the icon next to your name. Make sure it is a crown and has "Operator" ticked.