Drupal 7 Panel Edit icon missing

After logon as user with admistrator rights in Drupal CMS, the panel content edit (gear) icon is not shown in top right corner for each of them.

One Fix will be enabling Contextual Link Module under “Core” Module list

The content edit icon re-appear in Panel Page after enabling “Contextual Link” Module:

Note: this is not the same function for “In-Place Editor” under “Renderer” Section in Panel Setting:

This will add two button “Customize this page” and “Change Layout” at the bottom of the panel page. This has nothing to do with the editing content inside panel, but re-organization or adding/removing content in the panel layout: