You can opt out of NSFW content in your account on each instance. I think you've identified a need for us to add an override option on the app to apply when you're looking at content from servers you've not logged in to, is that right?
I think the issue is partly with the account switcher system, which seems to actually be an account combiner.
I have an account on lemmynsfw.com and an account on lemmy.world, and rather than basically letting me switch between the nsfw set of settings and communities and my normal set like other lemmy apps and reddit apps, it combines both sets of communities into one view which really isn't ideal.
I get that this is set up differently on backend a little bit, but it would be nice if this was done more like other apps, or at least had a way to set it up like that.
I would like to see the "block community" option added to the overflow menu for posts in the feed, so I don't have to open a post to block the community it is from.
Within the app, go to your profile, then settings (top right), accounts, select your account. You can now edit the option to show NSFW, toggle it off & save.. As for communities yes you can block a community....from the selected community page..hit the 3dots for that option..
You can also block a community by opening a post from that community and using the overflow menu.
I would prefer to see the "block community" option added to the overflow menu for posts in the feed as well so I don't have to open a post to block the community is from.