This was a question I recently asked because I was making a post and when I clicked the "submit reply" button at the bottom of the text box, I discovered that I was no longer logged into the website and I lost my post.
While I am not particularly skilled at simplifying answers to questions like these, this is what I found out about my situation.
The reason why I inadvertantly was logged out when I thought I was logged in, had to do with the "Browser" I was using and not the usual issue of needing to clear out the cache of cookies that your OS stores in the section of your OS called "history".
I'm a self taught technology geek and my notebook is not the notebook is was when I bought it. My notebook now has two different platform browsers. One platform is "Firefox" and the other platform is "Flock".
In my case, I needed to be in FireFox browser mode.
Not the other. I'm still working with the other browser
and learning what I can and cannot do with my other browser.
So, if you're having a browser issue, you might need help other than the tiny bit of help I left here. I had to ask a tech geek friend of mine about my issue because I just wasn't 'getting it' until they sat down with me and showed me, on the twin OS I have on my notebook, what my specific issues were.
I am healed, for now.