oooooooooooooh, now i finally get what's going on. i was getting afraid i'll just be perma...

Could you please explain for me?? I'm so confused right now >_<

i don't know how far back you want me to go. after the survey corps freed the island of all the titans, there was a time skip. most of the characters from the last few chapters are totally new (so no wonder no one knew wtf was going on). i have no idea how important it is to actually remember them, but it seems that a lot of them (especially the kids/younger people) are the ones that will inherit the titan shifting powers from the current generation. also i guess they're super bffs with reiner.
basically, the last few chapters where everyone got confused are happening in marely (reiner's side). they are showing the marley military fighting other nations and they are getting their ass kicked. they are relying on the titan shifters' powers, while the other nations developed technology that could defeat even the titans. so now marley is fucked.
so now their plan is to go to the island and get the founding titan's power (which eren holds right now, ever since he ate the king in the cave if you remember). that would give them a super strong titan army, because the founding titan can control all the titans. the problem is that eren and armin and the survey corps are being total bad asses protecting their island. they're totally destroying all the ships that marley sends to the island, so marley has no idea what's going on there.
SOOOO, that was a little all over the place. but did i make it at least a little bit clearer?

Wow, thank you!!! Now I get it (●'◡'●)ﾉ

Ahhh I got it ＼＼٩(๑`^´๑)۶//／／ Thank you so much for explaining~~ yeah all the new characters got me like @_@ Now im caught up with everything thats going on

But wait.... when did eren eat the king? I might've missed it or something
┗( T﹏T )┛

yeah, you're right. sorry, i got mixed up OTL eren got the founding titan's power from grisha, who got it from Frieda Reiss.
I totally got confused by the arc with the king and Historia and Eren, when they were underground. There was a lot of talk about eating, but no actual eating happened.