Logic Pro X Instruments don't sound right

Well, this is unusual, because I've searched the internet and couldn't find anyone with this issue.

I have a midi keyboard hooked up to a Mac, and whenever I play on the keyboard with a track selected, Logic plays the notes, but not on the right instrument. OK, technically it is playing, but I hear a much louder string part playing the notes with the instrument and overpowering the sound so I can't hear what the notes would sound like on the instrument I intend them to be on. This happens during recording, too, but when I stop recording and listen, the string parts are gone and I hear the instrument on its own.

Can someone tell me how to fix this, please? Thank you!