signal desktop file manager: how to change or choose a different file order

Hi, on my leap 15.3 with KDE plasma 5.23.5 and dolphin 21.12.1 using signal desktop version 5.24.0 when I save files from signal a unknown filemanager window appear like in picture
this filemanager has a strange file order, first files and folder with capital letter in alfabetical order then then folder and files with non capital letter, how can I change the filemanager used by signal and use dolphin or change the order of the folders and files of the unknown filemanager used by signal desktop?
manythanks ciao pier