Permanently changing the order of tracks in a playlist is only available through web browser to users on a desktop/laptop or tablet.
It's only possible to make permanent changes to your personal playlists or collaborative public playlists.
- Login to Deezer using a web browser on a desktop computer or a tablet
- Go to the playlist you want to update (My Music > Playlists > Select your playlist)
- Make sure your playlist is set to order Manually