Problem/Bug Default members have a "world" prefix

I have tried many things including re-installing group manager and messing with the config. Default members have the prefix of the world they are in before their name,
https://gyazo.com/2c5eab4efbc0b383191d65bee2974a68
My plugins are:
InfinityPvP(Custom) I've had this problem before this plugin
1vs1
AntiAutoclicker
AntiBuild
AntiMobSpawn
AutoBroadcaster
AutoRespawn
BattleCombatTag
Buycraft
ChatColor
ClearLag
ClickWarp
Combatkits
CombatLog
CommandSpy
EasyPortal
EnjinMinecraftPlugin
Essentials
FancyTab
GroupManager
KillerMoney
Multiverse-Core
OITC
PluginMetrics
PvPScoreboard
Reporter
ScoreboardStats
StaffApply
Tablist
TagAPI
Updater
VoxelSniper
WarpPortals
WarpSigns
WorldEdit
WorldGuard
I have had this problem for a while now and no one knows what to do, the server IP is theinfinitypvp.mcph.co
there is an error log in GM, it looks like https://gyazo.com/46944b734b745934aad56738d78eaa4a
What should I do?

 

The error log says that you haven't got a default group.
If you look at this group manager file http://pastebin.com/cGskUcug
Right at the top below the group name it says default and either true or false.
You've either not got any default group or you have more than one.
If you cant fix it yourself make a pastebin of your group file and ill try fixing it.

 

I can't figure it out. Here's the pastebin:
http://pastebin.com/DA7EQpy9

 

@ImmKelz

Try disabling the world prefix in the Multiverse config.yml or worlds.yml