There are various ways to achieve this for easy or complex changes.
As already mentioned, QnA’s or FAQs are a really good way to communicate changes and how to resolve them.
Surveys: these are great to identify any difficulties in new systems and a general feeling of acceptance of the change. Which you can also add to the FAQs. I am never afraid to listen and adapt FAQs to items or circumstances that may have inadvertently been overlooked.
Communications countdown: I usually issue comms on a 5, 4, 3, 2, 1 week push basis for information. Pull info is great, but if pending users ignore the links, they will/may miss valuable information and may stay longer in the dip.
Floor walking: FW is great as it gets you in the weeds and then you are on hand to advise in the first instance or advise where additional information can be found.
Workshops or Training events: These I usually like to do in small groups, and can also break them up into smaller tranches and several events to aid learning, though this is dependent on any time restraints of course.
User groups: as discussed in the training, some individuals learn better when shown as new task. Knowledge Transfer, when conducted effectively, is always a preference. I remember when I took my ECDL, I was taking the Foundation Excel module at the time and the Trainer asked a person by the side of me, are you OK with what you are doing. They replied, yes I’m OK, I’m just watching what Colin does..