As above. There are 3 buttons numbered 1 to 3. These are the memory buttons, giving 3 memories for the seat and door mirrors.
Sometimes if a replacement battery isn't connected smartly (terminal not allowed to spark) it sends voltages through the electrical system which upsets the controller modules (there are over 30 in an HSE), so I expect the seat memory module has got corrupted. The best thing to do is to disconnect the battery for a few minutes, then connect it again properly, by slapping the terminal onto the battery quickly to prevent sparks.
Once done, look through the owners handbook on how to reset the windows, seats, infotainment system and whatever else needs resting after the battery is reconnected.