This is starting to annoy me. I don't know what is wrong with what we have already told you many times already.
Let's say that you upload a file named "Fantasmón_sin_sus_lentes-Los_veo_allá.png" and your file naming is set to original. What happens is that the system will generate URLs like these:
View attachment 1927
If you or someone else uploads a filename with the exact same name (and at the same day when you use data folders) the thing can't use the original name because there's ANOTHER file already with that name. So the thing mixes the original name with a random string:
View attachment 1928
TL;DR: Long as the filename already exists in the target upload folder, the thing will have to append a random string to the newly uploaded file.
If you change the file naming method the changes will only affect NEW UPLOADS, old content won't be updated to match your current file naming by any means. The filename is static and won't change if you alter your settings or if you edit the image values. The filename has to be fixed and permanent and its value is taken directly from the original image. Users can't pick the name, it will take it from the actual filename.
Please do me a favor and understand how the thing works because I took the time to explain this to you with enough detail. Either you just want to annoy me or, well... anyone can make their own judgement here.