It is not 7

You should be prompted when opening after updating to the latest version.

Bell icon at the top right. Should bring up your inbox which holds your replies and messages.

I set a link in my profile to All/Hot/Page 0 for Lemmy.world, following the link seems to work in the PWA. You could put page 0 links for the different filters as well. Crude workaround, but it works!