Hi Deniz
The screenshot you've provided suggests that you are using a customisation that provides the clone tiddler button. That customisation dates from long ago in TiddlyWiki's beta phase, and is no longer necessary since the clone tiddler button is now included in the core.
To enable the core clone tiddler button, you just need to open the tiddler info panel with the lower case "i" icon, and then click the checkbox by the "clone" button.
To remove the obsolete customisation:
* Open the advanced search tiddler by clicking the three dots "..." next to the sidebar search box
* Switch to the "Filter" tab
* Type the filter expression "[tag[$:/tags/ViewToolbar]]"
* One of the displayed results should have a title that indicates that it contains the clone tiddler button
* Delete that tiddler
* Save and reload
Let me know if that works for you,
Best wishes
Jeremy