title: How do I change settings of a custom widget in kivy?
body: <p>I have this code where I want a button to trigger a change in a custom button. My solution only changes the color of all the custom buttons when they have been pressed. What would be the proper way to change the buttons?</p>
  
  <p>python</p>
  
  <pre><code>class B_SettingScreen(Screen):
      def change_color(self):
          Factory.MainButton.background_normal = "z_MainButtonColorRed.jpg"
  </code></pre>
  
  <p>kivy</p>
  
  <pre><code>&lt;MainButton@Button&gt;:
      font_size: 18
      markup: True
      size_hint: 0.25,0.06
      color: 0,0,0,1
      background_normal: "z_MainButtonColor.jpg"
  
  &lt;B_SettingScreen&gt;:
      MainButton:
          text: "[b][font=Arial]Change Color[/b][/font]"
          pos_hint: {"center_x":0.25, "y":0.5}
          on_release: root.change_color()
  </code></pre>