After ‘sign up’ or ‘sign in’ in the menu become visible links for ‘registered users’, but once I refreshing a page in the browser or open another page on my web-site — It automatically ‘logs out’ me and this specific link in the menu becomes invisible.
Why it is like this and how can I fix it?
Thanks
Hey Cyryl 
Welcome, and thank you for posting in the forum! 
Can you please make a loom.com video of the problem? This will help us figure out whats going on. Usually when this happens its because you are going from a secure site to a non secure site. Meaning the url is http://something.com and when you login it goes to https://something.com and on the https site you are not logged in. Try forcing https to be used all the time and see if the problem persists.
Dear Josh!
Thank you very much! Thanks a lot for your product — it works super great!
Yes, this is was a problem, if i use https — everything works correct!
Thanks