Only moderation staff can move posts to a different thread. If you have a post that you think should be moved, you'll have to ask a staff member. The easiest way to do that is to use the report feature.
To report a thread in Tapatalk, tap the thread you wish to report (it will highlight and you will see this pop-up:
Tap the report button to get another pop-up:
Press the "Report" button and you will get a text input to write your report. Then hit "Ok" to send the report. The staff will get your report and will take any necessary action.