***** NOT A TEACHER *****
Hello, Lilly:
I, too, get confused with the word "welcome."
It might help to remember that "welcome" is an adjective. For example, when someone thanks you for a favor, you reply "You are welcome."
It is a verb in "You are welcomed." For example: "When you visit Hawaii, you are welcomed by a lei [a string of flowers] being put around your neck." That is to say, "They welcome [verb] you by putting a lei around your neck."