Users do not always need to manually select a Transaction Site every time they enter data. Instead, a specific site is always selected as default. Naturally, this default site should be site where the staff person most often works.
A user's default site is the one to which their user account is attached. While user's can be granted multi-site access (as pictured above), these multiple transaction sites cannot be selected as default. Instead, when creating new user accounts make sure you select the most appropriate site for that user based on where they spend most of their time.
