Customers are the reason theaters are open. If the theater patrons do not come and spend their money, you will not have a job selling them tickets or helping them find their seats. Tickets to movies and plays are more expensive than ever, and your patrons do not want to have their night out spoiled because an usher was rude to them. People have plenty of entertainment options and if the staff is rude, your customers will find another theater to visit. It is of the highest importance that the lobby staff treat the customers with courtesy and respect.
Even if you have certain customers that are rude, you will find that in most cases people will react more positively to a polite attitude. Do not escalate with a rude patron. It will only make things worse and it will only hurt you in the long run. If a patron comes to you with a problem and is angry or upset, start by saying how sorry you are there is a problem and that you will do whatever you can to help. Almost everyone will calm down once they realize you are honestly trying to help.
If a customer persists in being rude or abusive, excuse yourself and tell them you will find them a supervisor to talk to. If worst comes to worst, you may need to get a security guard to help. You will never, however, make it better by yelling back at a customer, no matter how good it may feel in that moment.
Sometimes, you'll have to think on your feet to make sure all of the customers get what they need. It can be as simple as asking people in a row to slide over a seat to accommodate an extra person. You may have to find a new seat for someone in a wheelchair who didn't know there was no elevator to the balcony when she got her ticket. You may need to seat latecomers in a back row before they can move to their seats at an appropriate break in the action.
However, do not promise things you cannot deliver. If a patron is unhappy with his seat, don't tell him you'll move him to the front row or refund his money if you know that won't be possible. That will make the customer angry and get you in trouble.
Customers will have very basic questions that you should be able to answer. Which way are the restrooms? Is there an elevator to the balcony? How long is the show? When is intermission? If you don't know the answer to these, find out before you start to work!
It also is important that you know where all the sections of the theater are before you start seating people. This may seem obvious, but it is surprising how often ushers don't know where they are supposed to be sending you. Look at a seating chart or take a walk through the theater before you start work so you know where people will be going.
It's also important you be familiar with all emergency procedures, such as evacuation in case of a fire or even where the fire alarms are. This is information you need to know but will hopefully never have to use.