Making arm welds?

So I'm trying to make my own arm weld angles but when I change the C0 or C1 in command bar in play solo mode it doesn't do anything, or update. It would be easier to do it in play solo mode than hit play solo for every little change in the script.

*portion of the local script in the gun im working on

function Equipped()
    local RArmWeld = Instance.new("Weld")
    RArmWeld.Name = "RArmWeld"
    RArmWeld.Parent = Character
    RArmWeld.Part0 = RArm
    RArmWeld.Part1 = HumRootPart
    RArmWeld.C0 = CFrame.new(-0.75, -0.4, 0.35) * CFrame.fromEulerAnglesXYZ(math.rad(-90), math.rad(-15), 0)

    local LArmWeld = Instance.new("Weld")
    LArmWeld.Name = "LArmWeld"
    LArmWeld.Parent = Character
    LArmWeld.Part0 = LArm
    LArmWeld.Part1 = HumRootPart
    LArmWeld.C0 = CFrame.new(-0.35, 1.4, 0.6) * CFrame.fromEulerAnglesXYZ(math.rad(290), 0, math.rad(-90))
end