Where can I change sound of notification?

[Aquer]

In the newest versions Aqua (A few) we can not change sounds of notifications. Actually we can but in settings of Android only. (Aqua direct us to settings of Android) but when we change sound in android settings all my notifications are changed. I would like to change sound of notification Aqua only. (Like it was in olders versions) Can you fix it / correct it?

[patrickdrd]

you can add any sound (e.g. mp3) in /storage/emulated/0/notifications and it will be recognized for usage by aquamail,
that's what I did recently and it works fine

[Aquer]

I can not see this path. Tell me exactly where can I find it - via computer or phone and where should I start?

Iv got:

Settings>My files> and...? Internal memory or external? and whats next?