The Church does not choose saints, only God can do that. However, the Church does have an investigative process to determine if the person is actually in heaven called the canonization process.
They choose a patron saint so that their parish will come under the protection of that particular saint and to give honor to that saint
You choose a saint's name when you are baptized, and you may choose another saint's name when you are confirmed.
By first writing a letter to your parish priest, requesting to be Confirmed in the Church. Then partake in Catechesis classes. Then choose a Patron Saint. Then become Confirmed in the Church.
Technically, someone has to be dead to be declared a saint.
Saint Leo the Great was declared a Doctor of the Church by Pope Benedict XIV in 1754.
Someone doesn't necessarily want to be a saint. To be a saint you have to be dead and three miracles have to happen after someone prays to you.
The person is canonized, officially recognized by the Church as a saint.
they become a saint
It means when did the saint get canonize or when did the Church declare that person to be a saint. Canonization/canonize is when the Catholic church declares a dead person to be a saint. It's a long and lengthy process to declare/canonize a person to be a saint.
To be declared a saint by the Church you must first die.
They are said to be canonized.
By the strict definition of the church angels cannot become declared saints. Nowhere in the Bible does it call an angel a saint.Roman Catholics, however, often refer to Michael as "Saint Michael" but this title does not indicate canonization as it would a person.Archangel Michael s generally referred to in Christian litanies as "Saint Michael", as in the Litany of the Saints.Catholic AnswerThe title "saint" in the Catholic Church just indicates that someone is in heaven. The good angels have always been in heaven and thus the title "saint" applies to them. The Catholic Church, which wrote the Bible, is the same Church that applies the title to anyone in heaven.