After you upgraded to the latest version of YAML for Drupal you no longer need to install Panels layouts manually into the Panel modules folders.
The YAML Theme
yaml contains a folder named plugins/layouts that contains all the previously known YML Grid Templates. If you are upgrading from a previous version of YAML for Drupal you can just copy the folder into your existing theme folder and add one line to your yaml.info file.
; Panels layouts
plugins[panels][layouts] = plugins/layouts
The new grid templates also add a CSS file with YAML Grid CSS. This allows the seven theme as one example to display the preview of layouts correctly. In past the columns have been shown stacked in preview and only in live mode correctly.