Show short joins/parts
Checking this option makes mIRC display the join and part messages in a different, more compact format.
Show user addresses
Display user addresses in events such as joins/parts/quits/invites on channels.
Show nicks on join
Displays channel nicknames in the status window when you first join a channel.
These set the default flash option for any newly opened channel, query, or dcc chat window.
Skip MOTD on connect
This makes mIRC hide any MOTD information which the server sends you when you first connect to it.
Hide ping? pong! event
Occasionally an IRC server will send a ping to mIRC to check whether it is still connected. If you prefer not to see the "Ping? Pong!" message in the status window you can enable this option.
Cancel away on message
If you set yourself as away using the /away command, selecting this option cancels the your away status automatically the next time you send a message to a channel or a query/chat window.