i have rented 2 HD movies and not playing atmos, the 4k movie play atmos, on the 2 HD movies the atmos symbol disappears after rented

Please be specific about the rented titles, so that there is something to check. And also please specify your country for the iTunes Store (same as the country for your Apple ID account), as audio specifications may be region-specific. Not all titles have Dolby Atmos audio. It seems more common with newer 4K titles, although technically possible with HD titles. Dolby Atmos playback is dependent on your audio setup. Downloads (instead of streaming) may have different specification, in accordance with settings for that. For persisting issues, you may contact the iTunes Store staff, then they can look into it.

Play audio in Dolby Atmos or surround sound on your Apple TV - Apple Support

Find movies with 4K, HDR, Dolby Vision, or Dolby Atmos in the Apple TV app - Apple Support

Rent movies from the Apple TV app - Apple Support