I am primarily an iOS app user, so I do not know if this is happening on the website. I furthermore am using Decks courses and not official Memrise courses.
A few days ago, a change occurred in the way new words were introduced to me. Formerly, a batch of seven words would be introduced together. I would be introduced to all of them in one mini-session, strengthen them in a second, and complete all seven words together in a third session.
Now, in each mini-session I have seven words going at once, but they rotate in and out. Two or three are introduced each time, and two or three are completed. I find this extremely distracting, and wish I could find a setting to change that back. I assume the developers have a good reason for making this change, and it probably works for lots of people, but it does not work for me–it makes learning new words frustrating instead of fun.