Can I change the type of my visa from B1 to HB2 once in the USA?

I want to go to the USA for volunteering under a B1 visitor or VWP visa, I wonder if after my volunteering activities there I can search for a paid job and then chage my type of visa accordingly to HB2. The reason I ask this is because normally B1 or WVP have a maximum amount of days and I wonder how long it would... show more I want to go to the USA for volunteering under a B1 visitor or VWP visa, I wonder if after my volunteering activities there I can search for a paid job and then chage my type of visa accordingly to HB2. The reason I ask this is because normally B1 or WVP have a maximum amount of days and I wonder how long it would take to obtain the HB2 visa. Thanks
3 answers 3