I was signed out of my apple ID for no reason?

Went to check my emails on my phone and I had been signed out. I checked other apps and I was signed out of them as well. However there were a couple that weren't singed out. these were apps that I hadn't connected to my apple ID or used icloud to save my password. So I went on to my settings to find that I had been signed out of my apple ID and icloud. once I entered the settings a screen popped up say something like "please sign into your apple ID". So I did. Then I imminently got another pop up screen saying "please sign into your icloud". So I did. but then it just kept coming up over and over saying "please sign into your icloud" and I know I didn't get my password wrong, because I tried an old password and it said "login failed" which means it recognises that my password is correct. I also logged into and apple ID with the same password on my pc to create this post. I turned my phone off and on again and everything seems to be working. However, I'm still signed out of everything like my emails, social media and anything else I had used icoud to save passwords for. Like whats the point of icloud if it doesn't save a password after you sign out? The gmail app would not have made me sign in again if I hadn't told my icloud to remember my password. And why did icloud sign my out of almost every app I own because it decided to log me out of my icloud. I asked you to remember my password, not be what decided if I'm signed in with my gmail password!

It feel like everyday apple gives me a reason to switch to Samsung. Like apple looks nice on the outside, but it's rotten to the core. And I realise I'm using an older model (iphone 6s), but the phone itself is only just over a year old. 16 months from out of the box and it feels like I'm using a iphone 4. but that's a different issue...