The songs and instruments don´t match.
Hi! When I record it sounds nice, but when I listen to it afterwards the voice doesn´t match the instrument, WHY 
well, you need to learn how to use compression, eq and reverb to make it sit in the mix.
try looking up the
eq primer
on google.
sound on sound has a good reverb explaination. anyone here can answer these questions too, but be warned, it’ll take a LOT of practice before the desired result is reached. it’s tough to do.
Just out of curiosity, what do you mean when you say that the voice doesn´t match the instrument? Do you mean that they are out of sync?