How to Setup Apex Sharing Reason and Recalculate Class

TLDR... go to classic mode and view the custom object page.
Remember... this isn't a thing for built in objects... just custom ones.
Documentation:
help.salesforc...

[@koustubhjoshi8528]

Thanks for sharing. It was confusing.

[@IkeWaghSF]

Thanks for sharing (no pun intended)! This stuff is always confusing for me. Appreciate the video!

[@KateKitcho]

You still have to go to Classic to do this? Lol. Thank you so much, this was very helpful

[@kumar.anupam]

Thank you ! Now i will pay attention at the top of documentation :-).

[@ephetehemokgopanyane7165]

Thank you very much

[@KiranKapila]

Thanks for sharing

[@xinli5659]

thanks, you saved my day