Sorry if you don't like this. You have to remix this.First you have to click the see inside button.Then put the mouse pointer on the stage (Not to the username) then click the right button of your mouse.After that you will see a button 'save picture of stage'.Then click on it and choose a file on your computer (like- desktop).Then you will be able to set it on your profile!
Credit to @My_Dream_Logo Credit to @Bumoaf Pls follow them both!!