Sorry, I can only respond in English. With "Always Ask" (sempre preguntar), Firefox will always save the file to disk. You can change from using your Downloads folder to using the Windows Temp folder if you prefer. Here are the steps: (1) In a new tab, type or paste '''about:config''' in the address bar and press Enter/Return. Click the button accepting the risk. ''More info on about:config:'' [[Configuration Editor for Firefox]]. ''The moderators would like us to remind you that changes made through this back door aren't fully supported and aren't guaranteed to continue working in the future.'' (2) In the search box in the page, type or paste '''browser.download.start_downloads_in_tmp_dir''' and pause while the list is filtered (3) Double-click the preference to switch the value from false to true

Thank you, your solution solved the problem.