"Upload a file" is really not the best way to attach anything but a PDF or similar "file" - not an image - to your posts.
By the way, using a mobile phone browser to attach a file from the phone's Gallery or Camera is going to result in the "upload a file" kind of image display. There's no way around that because there is no desktop to drag and drop from.
By the way, using a mobile phone browser to attach a file from the phone's Gallery or Camera is going to result in the "upload a file" kind of image display. There's no way around that because there is no desktop to drag and drop from.