Hi! I agree with Victoria. When a person says "Encantada/o" is talking about herself/himself. So, if the subject is a woman, she says "Encantada" and a man says "Encantado". But when you say "Bienvenido/a/s" you are saying something to other people (Welcome). In this case, it depends on the object:
"Bienvenido" when talking to a man, "Bienvenida" when talking to a woman, "Bienvenidos" when there are many people and "Bienvenidas" when there are many women.
Regards,
M
