how do i change walking speed?

We can use a in pairsloop to loop through the Players to get the players that are currently in the server then we can use that information to change the WalkSpeed of the Player's Character.

for _,v in pairs(game.Players:GetChildren()) do--Getting the Player
	game.Workspace:FindFirstChild(v.Name).Humanoid.WalkSpeed = 50--Searching for the Player's Name in Workspace then it Changes their WalkSpeed to 50.
end

~ UserOnly16Charcters, Hoped I helped you to answer your question! If you have any further question, don't hesitate to comment below!!