why my old message always jump up to top again？

tonyjing,

If the device isn't already using iOS 16.3.1 (and is compatible with it), be sure to perform the update as that'll ensure it's using the latest available improvements: Update your iPhone or iPad - Apple Support

For unexpected issues with an app, it may also help in some situations to try force closing the app, and relaunch it: Close an app on your iPhone or iPod touch - Apple Support

iPhone X and later

1. From the Home Screen, swipe up from the bottom of the screen and pause in the middle of the screen.

2. Swipe right or left to find the app that you want to close. 

3. Swipe up on the app's preview to close the app

If you continue to experience issues you may also try reaching out to Apple Support for a further investigation: Apple Support

Cheers.

Hello tonyjing,

We see you're experiencing an issue with Messages. We'd like to learn additional details to help facilitate additional replies from the community. Let us know the following.

• Does this happen with iMessage or SMS/MMS messages only?
• Do you recall when this behavior started, and any changes to your device at that time?
• Does this happen for all contacts or only some?

These details and any you can provide can help. However, as a general starting point for troubleshooting, we always recommend trying a restart and also backing up and updating to the latest software version.

Restart your iPhone

Update your iPhone or iPad

Regards.