I know this is just for fun, but watch out for your reference pitches, even on fun songs. Your various parts of this song are in tune with themselves, but not with the backing tracks of the song.
I know you can get this on the money if you work it with your keyboard, but this particular demo (that isn't a demo, it's goofing around on a Bing Crosby song) is out of sync with the key of the backing track.
I would be more worried if I had never heard you sing on pitch, but this is an instance where the key you are hearing in your head is not the key we are hearing in our ears from the backing tracks.
I'm not picking on you, buddy. I know you're just sharing some Christmas fun. Don't let me spoil it for you. I'm just sayin'...
: ^ )
It's kind of a moving target. It's like at different places in the song you are singing in different keys. You need to reference the backing track a little more to keep your bearings, so that you will sing in the right key.
It's a little like those "favorite Posts" you referenced yesterday. In both of those, the person on the demo could have sworn they were singing the right melody to those scales, because in their head, they were "hearing" the right note when they sang an incorrect note on the high point of each scale.
If you start out on a wrong note and think it's right, everything from that point on will be off somewhere in La-La land. At different points you would start out on an incorrect note and proceed from there. Your pitch-seeking radar was not engaged. Once you start a line on an incorrect pitch, you will be in trouble.
This isn't very Christmassy of me, it's actually more Grinch-like, but your first note is a B-flat 3 on "I'm". It should be a G3. If you try to sing that song starting on a G it will sound a lot different than it does starting instead on B-flat.
"Just" (the first word of the next line) should be a C4. You're singing a D4. So you're off by a different amount there.
You may have to work through this with your piano. I know you were just having fun, and I spoiled it, but it will be even more fun if you can tackle this just like you did the exercises and your other recent demo. You're wanting to just sing from your heart, but your pitch-radar needs to be accurate constantly, 24/7, even when you're just having fun, if anyone else is going to be listening.
Eventually you will have this pitch thing nailed to the point that it's no longer a thing, but for now, as a friend and helper, I want you to know your pitch is kinda random in this, and I don't think you were aware of it. Just another lesson in the journey.
Check it out. Listen to the notes of the original vocal and see if you are doing it like Bing, or whichever version you want to do.
All the best!