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	user/dashboard	Area to be shown to the user after login. Possible values are: user/dashboard, user/calendar, user/record, rooms/my, rooms/group, rooms/public, admin/user, admin/connection , admin/group, admin/room, admin/config, admin/lang, admin/ldap, admin/backup, admin/server, admin/oauth2	2.1.x, values are changed in 3.0.0
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
swftools_zoom	100	DPI for conversion of PDF to SWF (should be an integer between 50 and 600 with a default value of 100 DPI)	2.0.x
swftools_jpegquality	85	Compression quality for conversion of PDF to SWF (should be an integer between 1 and 100, with a default value of 85)	2.0.x
sendEmailAtRegister	0	User get a EMail with their Account data. Values: 0(No) or 1(Yes)	2.0.x
sendEmailWithVerficationCode	0	User must activate their account by clicking on the activation-link in the registering Email. Values: 0(No) or 1(Yes) It makes no sense to make this(sendEmailWithVerficationCode) 1(Yes) while sendEmailAtRegister is 0(No) cause you need to send a EMail.	2.0.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
allow_frontend_register	(configurable during install)	Is user register available on login screen	1.8.x
allow.soap.register	1	Is user register available via SOAP/REST	3.0.x