Files in your local folder are shown in the LEFT table with a light blue background
You can change the sort-order of the files in both tables by clicking the column-header or by using the relevant sort menu items. In the local files table the checked items can helpfully be shown above un-checked items to clarify what is next to be uploaded.
You can check or un-check the files in the local table to reset their status -

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Files to be Uploaded in the next session are shown checked and are displayed in blue. Their checked status will be cleared after they have been uploaded. Files that have been successfully uploaded and do not need to be included in the next session are shown in red with their check-boxes cleared. The menus provide many options to revise the status of selected blocks of local files.

Files in the website folder are shown in the RIGHT table with a pale green background

The Direct file Management menu provides many ways to set the File Upload Manager to -
  ●   Upload checked  or selected local files to your website
  ●   Display individual local or remote files (in your browser)
  ●   Delete individual local or remote results files
These features allow you to do much of your results file handling from within this Explorer environment, in a similar manner to the capabilities offered by most FTP clients.
When you click to upload some files the ACRO Upload Manager will be displayed and the process continues in the usual way, returning to this Explorer interface when the session is complete.

You can also Right-Click to Upload, Display or Delete individual files
Select the "Show" option to open and display a local
file in the appropriate / default application.
You can also delete a file from the local or remote folders by selecting "Delete this file". Note that this step can not be undone so be sure to delete only files that you know can be replaced or are unused.