user name accounts

i have 1 pc 1 user connected to a NAS. im trying to set it up for different
users with different passwords. so far im setting up three users with
different access levels. i want to test out each access but once i log in
with the "connect to..." "username/password" i cant log out to sign in with a
different user without restarting the computer. so my question is; is there a
way i can reconnect to the NAS with a different username/password without
restarting? if so how?