If you want to change your yahoo mail password, it is not mandatory to have a laptop, you can change it through the mobile application. I will show you the complete steps.
Change Yahoo Password through mobile apps:
1. Tap the Menu icon Image.
2. Tap Manage Accounts.
3. Tap Account info.
4. Tap Security settings.
5. Enter your security code.
6. Tap Change password.
7. Tap I would rather change my password.
8. Enter the new password and its confirmation and tap Continue.
If your password didn't change yet. you can simply visit the given website.