Hi @matej

In lattest B2Evo 6.9.2b there is no
.../cache/ sub-directories
only
.../_cache/ sub-directories
Is this same? Should I change it to 774???

If you're taking this page as a guide: http://b2evolution.net/man/directory-and-file-permissions, it's a bit outdated. Some directories have been renamed, as the case of _cache. Permissions should be set as mentioned in the page: This requires exactly the same permissions as the media directories...

In lattest B2Evo 6.9.2b there is no
.../blogs (directory)
.../blogs/skins/custom (directory)
So where can I find them to change permissions.

Exactly the same case of above.

I have deleted "sample".htacess to have only ".htacess" is this enought?

Yes, it's enough.

On my webserver I have:
logs
subs
web (there is .htacess in directory)
.htacess (first htacess - 0 size)

In web there is b2evolution installation...
Should I edit first .htacess too?

You should replace the previous /web/.htaccess file with the one shipped with b2evolution and mentioned above.