In Administration > Configuration there are a number of configuration values.

key	default	meaning	availabe since OpenMeetings version
user.login.minimum.length	4	minimum chars required for the login to create a user	1.9.x
user.pass.minimum.length	4	minimum chars required for the password to create a user	1.9.x
number.minutes.reminder.send	15	minutes the one-time reminder in the calender is send, set to 0 to disable reminder	1.9.x
max_upload_size	1073741824	Maximum size of upload file (bytes) 1073741824 bytes = 1GB	1.8.x
show.whiteboard.draw.status	0	Display name of the user who draw the current object (User Name auto-disapper after 3 seconds.	1.8.x
use.old.style.ffmpeg.map.option	0	If the system should "." (old ffmpeg) instead of ":" (new ffmpeg) for the -map option in FFMPEG	1.9.x
inviter.email.as.replyto	1	Set inviter's email address as ReplyTo in email invitations (1 == set, 0 == NOT set)	2.0.x
office.path		The path to OpenOffice/LibreOffice (optional) please set this to the real path in case jodconverter is unable to find OpenOffice/LibreOffice installation automatically	2.0.x
default.landing.zone	dashboard.rooms	Area to be shown to the user after login. Possible values are: dashboard.rooms, dashboard.chat, calendar, rooms.public, rooms.private, rooms.user	2.1.x
sms.provider		SMS service provider (bulksms.http.1)	2.1.x
sms.Username		Login for SMS service provider	2.1.x
sms.Userpass		Password for SMS service provider	2.1.x
sms.subject		Subject of SMS reminder message	2.1.x
redirect.url.for.external.users		Users entered the room via invitationHash or secureHash will be redirected to this URL on connection lost	2.2.x