Character glitching when changing the arm CFrame. How do I fix this bug?

This is a thing about player's characters. Since they have joints inside of them, when you move one part, all the parts move with them. A easy way to fix this is the following:

local arm = player.Character:WaitForChild("Right Arm") --get player's right arm
local newarm = arm:Clone()--clone it
newarm:ClearAllChildren() --get rid of all the joints in it
newarm.Anchored = true--anchor the part (cframe's dont work well with unanchored parts)
newarm.Name = "Rightt Arm"--name it something else
newarm.Parent = arm.Parent--put it in the plr's character
arm.Transparency = 1 ---make it non-visible


local function MoveTo(cframe)--this function will move the player's arm to the position
    arm.CFrame = cframe
end

Now, you could simply make the LookAtMouse like this:

local function LookAtMouse()
      MoveTo(CFrame.new(player.Character:WaitForChild("Right Arm").Position, mouse.Hit.p))
end

If your not doing this already, this would need to be run in a while wait() do loop or game:GetService("RunService").RenderStepped loop for it to be constantly updating, I hope I could help you with your problem,

-REALTimothy0812