To change a Vue prototype variable in all components, we can use Vue’s mixin functionality.

Mixins allow us to inject functionality into multiple components.

To do this we:

1. Define a mixin that modifies the Vue prototype.
2. Import and use this mixin in your main Vue instance or in any components where we want to apply the changes.

Here’s an example:

// mixin.js

export default {
  created() {
    // Modify the Vue prototype variable
    this.$prototypeVariable = 'new value';
  }
};

// main.js or our main Vue file

import Vue from 'vue';
import App from './App.vue';
import mixin from './mixin';

Vue.mixin(mixin);

new Vue({
  render: h => h(App)
}).$mount('#app');

Now, $prototypeVariable will be available in all components and will have the value ‘new value’. We can access it in any component like this:

// YourComponent.vue

export default {
  created() {
    console.log(this.$prototypeVariable); // Output: 'new value'
  }
};

Keep in mind that modifying the Vue prototype should be done cautiously, as it affects the global behavior of Vue instances.

Make sure we have a good reason to modify the prototype, and ensure that it doesn’t conflict with any existing or future functionality.