It is possible to change the file names of the files uploaded to Boardeaser. However, the files generated by Boardeaser, those files with a padlock after them, cannot be renamed.
To change the name of an uploaded file, you first need to open the document archive by clicking "Documents" and then "All documents" in the left menu. You can only rename files from this view.
Click the icon with three dots (···) next to the file you want to rename and select the "Edit" option.
Enter the desired file name and continue by clicking "Save".
The file name is then changed.