I applied to immigrate to the United States, and my immediate family is here, but I haven't arrived yet. I want to visit America first and sign another visa. Can I sign it?

Because you are going through the immigration formalities,

Visa officer can hardly believe that you will leave the United States after a short visit at this time.

Unless you have a particularly strong binding force at home.

Don't listen to those agents, you may be able to sign in less than one in a million.