The system manages a data structure that defines at least one topic limit for each client computer. The data structure can cause each client computer to display different user interface formats based on a topic limit that is allowed per thread. The data structure causes some devices, which may have a limited viewing area, to only show a single-topic thread, while the data structure also causes other devices to display multi-topic threads. Thus, for high priority topics or for devices having a limited display area, the system can cause the display of a single-topic thread pertaining to a topic to which an incoming message corresponds. This feature can improve user interaction by bringing focus to high priority threads when messages of a particular topic are received at select devices, while allowing other devices to provide a broader perspective of thread formats having multiple topics when the same messages are received.