I have tried copying files from music folder to RINGTONE present in phone memory but I am unable to get these tones displayed when I go to select a ringtone from settings menu !
I used AERIZE Explorer to copy 3 mp3 audio files which are around 30 sec long... How do I set custom ringtone on 8.1
Let me tell you an alternative way
[1] Download UC Browser to your phone.
[2] Download any song or ringtone of your choice from any website you know.
[3] You can set that song or ringtone as your ringtone by long pressing the song in Downloaded section.
Now, if you want to customize the length of the song downloaded for ringtone, you need a SD card to do so. Here are the steps:
[1] Long press the downloaded song/ringtone and "Export" it to the SD card.
[2] Download Ringtone Maker app from Nokia and select the song to adjust its length.
[3] Set it as ringtone.
Hope that helps!