To make Island your default browser on the Windows operating system, you can follow these steps:

1. Open the Start menu by clicking on the Windows icon in the bottom left corner of your screen.

2. Type "Default apps" in the search bar and click on the "Default apps" option that appears in the search results.

3. In the Default Apps settings window, scroll down and find the section labeled "Web browser."

4. Click on the current default browser (it might be Microsoft Edge or another browser) to open a list of available options.

5. Select "Island" from the list of browsers. If Island is not listed, make sure it is installed on your computer.

6. After selecting Island, close the Default Apps settings window.

From now on, any links or web-related activities should open in Island by default.