Ok i'm using this feature to not download the root folder (when existing) and some minor files.
It works well only when we don't want to download the smaller files,but sometimes i have to change the default auto-selection,maybe adding a smaller file or removing a big file.
whenever i change the auto-selection,the root folder will be created and this is not good at all!
Please fix this

PS:it would be also nice to see in the selection if there is a root folder or not. the folder is never shown.

All multi-file (more than 1 file) have a folder. With the name of the transfer. Period.
That's why the option says "if only one file, stick in main download folder" INSTEAD of making its folder.

i know that if i see more than 1 file there is a folder,but when the folder has 1 file i don't know if there is a folder or not
But this is not the main problem.

when i change selection the folder is always downloadad and i don't want this. That's why is bettere to see the folder and be able to select it or not,like it was a file

Ahh more clear, sorry I misunderstood.
Yes you want to use auto-select, ALWAYS auto-select, and DIRECTLY move file/folder under Settings -> Transfers -> Files

According to the features, when activated, and when only 1 file is used, the parent folder is not used, and your default/set "download folder" takes precedence.
Does this make more sense?

ok so we have 2 problems now! one of them i was not aware.

1) The folder is created every time i want to download more than one file inside a folder,also if i don't change the auto selection

2) Even if i want to download only 1 file,if the file is not the one auto selected,the folder is created

The should be an option to never create the folder.

Please list your settings for the options, and describe behaviour you expect.

The settings apply to NEW TRANSFERS only. You can clean up your downloads with Categories (Layout -> Categories -> sidebar/menu/column header) and apply to existing.

I'm not seeing the difference between your 1 and 2, sorry. Please use example like:
MY_FILE_2016-10-07\
--main_video.avi
--main_video_description.txt
--ad_for_video.url
--click_my_website.NFO

I can tell you when I have used the option it works for me, but I rarely partial seed like this no matter the extra stuff. It doesn't matter sizewise on my drives, and when I compile like-files it de-duplicates the miscellaneous for me anyway. So I have not tested this thoroughly as you have.
Since the feature has gotten a review several times and been changed in response BUT NOT changed recently, you need to be as thorough as possible when describing behaviour.