why does the gui break locally when the player resets or joins an old server?

so I have a gui, and if you reset, then the gui will go back to how it is in studio. also, if a player joins a server that is not new, then that person will see how it looks like in studio. also it will say "toptip is not a valid member of ScreenGui". heres part of my code

function underworld()

print("Underworld has been chosen") local plrs = game.Players:GetChildren() for i, v in pairs(plrs) do local gui = v.PlayerGui.gamegui wait(5) script.click:Play() -- Clicking noise wait(.2) script.click:Stop() gui.toptip.toptiptext2.Text = "The map will be chosen in 10 seconds" gui.toptip.toptiptext2.Visible = true wait(.8) script.click:Play() wait(.2) script.click:Stop() gui.toptip.toptiptext2.Text = "The map will be chosen in 9 seconds" wait(.8) script.click:Play() wait(.2) script.click:Stop() gui.toptip.toptiptext2.Text = "The map will be chosen in 8 seconds" wait(.8) script.click:Play() wait(.2) script.click:Stop() gui.toptip.toptiptext2.Text = "The map will be chosen in 7 seconds" wait(.8) script.click:Play() wait(.2) script.click:Stop() gui.toptip.toptiptext2.Text = "The map will be chosen in 6 seconds" wait(.8) script.click:Play() wait(.2) script.click:Stop() gui.toptip.toptiptext2.Text = "The map will be chosen in 5 seconds" wait(.8) script.click:Play() wait(.2) script.click:Stop() gui.toptip.toptiptext2.Text = "The map will be chosen in 4 seconds" wait(.8) script.click:Play() wait(.2) script.click:Stop() gui.toptip.toptiptext2.Text = "The map will be chosen in 3 seconds" wait(.8) script.click:Play() wait(.2) script.click:Stop() gui.toptip.toptiptext2.Text = "The map will be chosen in 2 seconds" wait(.8) script.click:Play() wait(.2) script.click:Stop() gui.toptip.toptiptext2.Text = "The map will be chosen in 1 second" wait(.8) gui.toptip.toptiptext3.Visible = true gui.toptip.toptiptext3.Text = "Map has been chosen!" gui.toptip.toptiptext.Visible = false gui.toptip.toptiptext2.Visible = false gui.map1.Visible = true wait(4)