The sound output for discs is different than games in the PS4. You need to set them each if I recall correctly.

Any disc player is supposed* to bitstream ATMOS or DTS:X media to the receiver to do the decoding after. In practice some dont and some receivers wont decode immersive tracks as legacy correctly without digital ticks and burps. In that case sending PCM from player is the workaround.

Ie. Atmos bitstreamed to some older AVRs wont decode as Dolby True HD as its supposed to.

If set to bitstream Dolby from the PS4 your options on your receiver should be Dolby Surround or Dolby Digital showing depending on how you set up your AVR.

AVR setting:
Direct= Dolby Digital or ATMOS depending on title. (Not sure many game titles render ATMOS natively)
Atmos upmix = Dolby Surround. (Do this even if you dont have heights)

What AVR do you have? Usually spells it out prettywell in the look up charts in the back pages of the manual.