I followed this guide to achieve that: 1) Open a new tab to about:config (type about:config in the Awesomebar and tap the go arrow or tap Enter). You may want to bookmark this for easier future access. (2) On the search line, type down and pause while Firefox filters the list (3) Scroll down to browser.download.folderList and tap it to display the editing controls. Change the value from 1 to 2 (from "default always" to "last used folder"). (3) Tap the large "+" above the list to add a new setting (A) On the right side, you see "Boolean" tap that and change to "String" (B) The name of the preference should be browser.download.dir (this stores the last used directory) (C) The value depends on the folder you want. For example: /sdcard/FxDown But when I try to download something, nothing happens. If I try to set an inexistent path or a correct path in the internal storage firefox will download the file in the default download path or in the correct path. I suspect that Firefox needs to ask the permission to write in the sdcard but it is not programmed to do that. Any suggestion? I have a sony xperia x on android 8.0.