You can use the below steps to change the color theme from the default theme to one of the available themes in your Azure Dashboard. To update the portal theme , follow the below steps
How to Change the Theme in Azure Portal ?
- Open the Azure Portal and login with your azure credentials.
- In the upper right corner, click Portal Settings menu.
- In the Portal Settings blade, select the theme under “Choose a theme“. Once you change your theme , your changes should be applied immediately.