Hi,

open your form in the design view.
go to your dataconnection dialog: tools - dataconnections
update your main connection. while updating your connection you can set the
checkbox for saving your password and user in your form.

the password and username are saved in cleartext!!! it is not save!!!!
all users will be connected through this one user you saved in your form.

if you are using sqlserver you can set the security settings for your user
in the sqlserver enterprise manager. i prefer the second way.

Andrej