What is the problem with assigning Android headset buttons?

Question

Android

There is a smartphone DIGMA Z560 4G CITI android 6.0 I have been using branded headphones from a HTC smartphone for a long time, there are 4 buttons on the headset (forward track, phone call, pause, back track). I constantly listen to music through the Vkontakte application, everything was fine, the buttons worked as they should, but today the buttons (forward and backward) began to adjust the volume instead of switching songs. The smartphone rebooted, I pulled out ten headphones, but the smartphone continues to change the volume instead of switching tracks, how can I solve this problem? The same headphones worked on a ZTE smartphone and everything is fine.
I did not install any programs for the day and did not update