Suggestion

1-There are ''Sign in'' in right top corner.

Please remove ''Sign in''. Please add ''Log in''.

2- I am log in. There are ''Sign out'' in right top corner.

Please remove ''Sign out''. Please add ''Log out''.

Because; sign=register.

I sign into work every day. "I'm reporting in"

Sign in, sign out is perfectly fine.

Definition -

To record the arrival of another or oneself by signing a register.

This is an english speaking forum, and in english to sign in is synonymous with logging in when on a website.

What you are talking about is "Sign UP"