Why do I see a string with a cloud and golden coloured?

These items are flagged as “Fuzzy”. This is a Gettext concept used in PO files.

You can toggle this flag in the editor if you need to:
https://localise.biz/wordpress/plugin/manual/editor#target

Fuzzy translations can be compiled into MO files, or ignored:
https://localise.biz/wordpress/plugin/manual/settings#mo

As to why you see them – either someone flagged them, or you flagged them, or they were flagged in some other operation like auto-translation. I can’t really tell you what has happened to your files.

Using TAB I cant remove the fuzzy status…

TAB is not used for removing the fuzzy status. As per the help page I posted earlier, you can use Ctrl-U, or the fuzzy button (with cloud icon) above the translation pane.