You need to set an username first. What does this mean?
Either you registered your account but have not set an username for it, or something may have gone wrong in the database. If you ever get this, just log out and log in again. The game will ask you to set a new username. Please set the same username you have used before. If you can't set your old username, please contact a moderator. If you want to set a new username, please read part 3.
Someone is annoying me. What should I do?
You can mute players by entering the command /mute <username> into the chat. You can then do /unmute <username> or rejoin the world to unmute the player. If that ignored player tries to annoy you without chatting, you can talk with the world owner, or kick them if you don't want them (on your worlds). If it's their world, you can just leave.
How do I type in a command?
World commands start with the / symbol. Use the /help command to get a list of available commands.
An user has a "X." on their username. How do they have it?
It's a bot. You can not get this prefix unless you create a bot, in which case you will need to use a special bot initialization message.
I kicked a player but they joined back. How did they join?
Kicking players will just get them out of the world, but not prevent them from joining. If you don't want them to join your world, try using the /ban <username> command.
Why can't I place the "T" text block?
Text blocks are disabled on the world and you don't have administrator access.