Changing player's default animation of choice to custom animation ID?

Upon tinkering with the player's character in the workspace, I found a LocalScript that contained Animations. In these contained the player's choice of animation, and I want to change that to a custom animation or a ROBLOX preset, like rThro.

Here's my attempt (LocalScript, Workspace)

local player = game.Players.LocalPlayer
local character = player.Character
local runAnim=character:WaitForChild('Animate'):WaitForChild('run'):WaitForChild('RunAnim')
local walkAnim=character:WaitForChild('Animate'):WaitForChild('walk'):WaitForChild('WalkAnim')

runAnim.AnimationId = 'rbxassetid://2510238627'
walkAnim.AnimationId = 'rbxassetid://2510242378'

However, the run animation works, but the walk animation is partially overriden by the player's choice of animation. (In my case, the cartoony walk.)

Any help?

(P.S, sorry about the format of the code block, I'm new and I don't know what to do about it.)

To change it, first go to test mode on your game. Then pause it and copy your character. Once done press stop and paste the character. Go inside and press Animation. Drag animation to StarterPlayer > StarterCharacterScripts. Once done, open it and find the name of the animation you want to edit. Then change the ID to your id.Go inside of the script and press the animation. Change the ID and wallah, its done. If you want to change animations with Weights applied, I think you could instantly figure that out. If not, reply to my answer and I will tell you.