How can I update my App Store

If you mean the App Store app itself, it is update when you install a system update.

If you mean apps from the App Store, read this article: How to manually update apps on your Apple device - Apple Support

Get live expert assistance by contacting Customer Support by phone or chat:

• Call 1-800-APLCARE. 📞
• International Support. 🌐
• Contact Apple Support. 📝
• Live chat using Messages. 💬

Good luck! 👋🏼😉