How do I make the rank change to the different groups ranks when I join a different team in my game?

local GroupId = 2595428

repeat wait() until game.Players.LocalPlayer and game.Players.LocalPlayer.Character and game.Players.LocalPlayer.Character:findFirstChild("Head")
local plr = game.Players.LocalPlayer
local head = plr.Character.Head
if plr:IsInGroup(GroupId) then
local gui = Instance.new("BillboardGui", head)
gui.Adornee = head
gui.Size = UDim2.new(100,0,1,0)
gui.StudsOffset = Vector3.new(0,3,0)
gui.Name = "RankGui"
local rank = Instance.new("TextLabel", gui)
rank.Name = "Rank"
rank.BackgroundTransparency = 1
rank.BorderSizePixel = 0
rank.ZIndex = 2
rank.Font = "ArialBold"
rank.Text = plr:GetRoleInGroup(GroupId)
rank.Size = UDim2.new(1,0,1,0)
rank.TextColor3 = Color3.new(1,1,1)
rank.TextStrokeColor3 = Color3.new(0,0,0)
rank.TextStrokeTransparency = 0
rank.TextScaled = true
rank.TextWrapped = false
end

My friend made this script for me and he said that the teams will change ranks when I join a different team. IDK how to edit this.. Can someone help me?