When referring to someone who holds a position of power or is responsible for making decisions, the phrase "are in authority" can be expressed in a variety of ways. Some possible synonyms include "hold power," "command," "govern," "oversee," or "lead." Other options might include "preside over," "manage," "rule," "administer," or "direct." Depending on the context, there may be additional words that could be appropriate, such as "enforce," "supervise," "regulate," or "influence." Ultimately, the most suitable synonym for "are in authority" will depend on the specific situation and the nuances of the language being used.