1. **Open the Instagram app**: Launch the Instagram app on your mobile device.
2. **Go to your profile**: Tap on the profile icon located in the bottom right corner of the screen to go to your profile.
3. **Access the settings**: Tap on the three horizontal lines or the gear icon (depending on your device) at the top right corner of your profile to access the settings menu.
4. **Open the "Settings" menu**: Scroll down the menu and select "Settings" at the bottom.
5. **Edit your profile**: In the "Settings" menu, tap on "Account," then tap on "Edit Profile."
6. **Change your username**: In the "Edit Profile" section, you'll see various fields, including your username. Tap on the field containing your current username to edit it.
7. **Enter your new username**: Delete your current username and type in your new desired username. Keep in mind that usernames must be unique and may only contain letters, numbers, periods, and underscores.
8. **Save your changes**: After entering your new username, tap on "Done" or "Save" at the top right corner of the screen to save your changes.
That's it! Your Instagram username has now been changed. Keep in mind that changing your username may affect how people can find you on Instagram, so choose your new username carefully.