Right after you log in, the window below displays briefly. Note the short-cut keys for quickly switching chat rooms. You can also use the 3-dot menu and click on the chat room that you want to use.
You can identify which chat room you are currently using by looking at the colored stripe at the top of the chat window. See the two cases below.
Also, note that the chat time stamps do not identify the date. If there a few entries on consecutive days it is hard to be sure when the date has changed.
John WA5MLF