I've done this before, and it's worked perfectly fine! I have no idea what's wrong with this script. Is anyone able to help?
script.Parent.MouseButton1Click:Connect(function()
script.Parent.Parent.Parent.MainText.Visible = true
script.Parent.Parent.Parent.MainText.Text = "Welcome."
end)

3 comments
Did you put the correct amount of Parents?
Yes
What if the particular GUI text isnt visible at the default setting? ( the box "Visible" is selected, or the text has an transparency of 1? )