clear your browser cache too.

>>1. The title disappear when icon disabled,

You can't disable icon within the widget's settings.

>>how to show only title but not icon?

  a) "Show title" should be checked.

  b) add following styles in admin panel>>edit theme>>CSS:

 
html body div .ow_ic_user {
    background-image: none;
}

Note that this will remove the 'user' icon from all places where it is used on the site.

If you would like to remove 'user' icon only from "Users" widget, you will need to edit  the .html files.

>>2. I found this when i post this, after I upload attachments, it will be great if I can just insert the image from the attachments list into the post now I have to upload another image from the image icon in the post, not very important but a suggestion

Thanks for the suggestion.