Turing machine and language decidability
A TM decides a language if it enters the accepting state for word in the language and it enters the rejecting state if it is not. Thus it halts on all inputs. Note the machines defined above are not entirely standard. They way they denote acceptance and reject is by writing a $1$ or $0$ and then by entering a halting state. This is equivalent to the standard definition, but less elegant.

Machine 1 does not reject words not in the language. It only accepts the language.

Machine 2 does not halt for words not in the language. It only accepts the language.

Machine 3 rejects and hence halts for words not in the language, therefore it decides the language.