Praise be to Allah.
The reports that have been narrated concerning appointing an ameer refer specifically to when people are travelling, because when people are travelling they need to be able to refer their opinions to a leader or ameer. But when people are not travelling, usually each individual is busy with his own affairs and they do not need an ameer.
But they may appoint someone to be the head of their society or group, so if for example they are living in a flat, they may say” we need someone to organize our affairs in this flat, so we will appoint So and so to be our head or ameer.” Then they can discuss with him the running of this household’s affairs, such as what kind of food to have, setting times of rest, deciding what needs to be bought, and so on, so they discuss these things with him and agree to accept what he says. This is correct, in sha Allaah.