Ae, pololei. The verb "put" should not be separated from its preposition "back" by the direct object "the phone." The prepositional verb "put back" should be the correct answer. Note that other prepositional verb phrases in ths lesson -- "turn on the light" and "turn off the light" -- are correct. Why not this?
It is often understood as a command without "ʻoe" because it begins with an "E"
'Ae. It is added to clarify or emphasize the actor in a command. If the context is clear, then it can be omitted.
I'm a native English speaker from England and I would also say that "Put back the phone" and "Put the phone back" sound equally correct.
I'm not much better in English, but if you have the word 'oe in the sentence you should translate the 'you' accordingly. Shouldn't you? If we are having a conversation with someone it's already understood who u talking about.. sometimes the app makes mistakes, but i still like.