ITunes isn't syncing all of my songs?

I have recently brought a new macbook. I have been syncing my iPhone to my mac COMPUTER for about a year and if I've brought the songs ON the phone they have always synced onto iTunes on my computer, and vice versa. But today I tried to sync my iPhone to my new laptop and only about half of my songs ended up syncing to iTunes. But then later tonight I brought songs off iTunes on the laptop and tried to sync my iPhone again so those songs would sync onto it, but they didn't. I'm not sure what's happening or why these songs aren't syncing. None of my songs are illegally downloaded and added to my library, they're all brought from iTunes. Help!

Added (1). I can drag songs on my laptop to my iPhone but I can't do it from my iPhone to my laptop.

How are young adults able to pay for their luxury cars?

And still be able to go out to clubs, concerts, have an iPhone, friends, school and a life? I don't get it?

IPhone 4s won't unlock while drunk?

Every single time I slide the the "slide to unlock" button on the iPhone screen to read a text it just kept bouncing back. I'm pretty sure my finger was moving accurately even though I was drunk. Does iPhone know I'm intoxicated or there's some kind of black magic going on? Has this ever happened to anyone else?

Do iPhones put the clocks back automatically?

I have an iPhone 4S and I was wondering if they automatically go back an hour for daylight savings time.

Can I buy a locked iPhone and then just unlock it?

I'm sorry for all my iPhone questions but I was wondering, if I get a locked iPhone from the store, would I be able to unlock it once I purchase it? Are there other shops or places wherein they could unlock the iPhone? It's just that, the locked iPhone is so much more cheaper so if I could get it unlocked after I buy it, then why not just buy the locked one if it's cheaper right?

Suggestions please? Thanks!

*By iPhone, I meant the 4S. But does it also work on the 5?

Added (1). More answers please?

How to access PC websites through iPhone?

I have to access YouTube through my iPhone, but the iPhone version has a bunch of limitations. I have to access the PC version through my iPhone 4S but I don't know how. I know that this is possible because I access Facebook through my mobile web browser with the PC version. How to do it with YouTube?

How to Jailbreak iPhone 4 ios 6.0.1?

I have tried unsuccessfully to jailbreak my iPnone 4 ios 6.0.1, I have tried numerous sites but each time it has failed. Is there a foolproof way to ensure this can be done?
I would appreciate any advice.

Is it possible for me to get a sim card in india for my iphone 4?

I'm South African and i will be on holiday in indi for a month… I would like to know the procedures for me to purchase a sim crd for my iphone… In this case it would have to be a micro sim.

How to use straight talk with iphone 3gs?

Iphone 3gs is used but great shape and has been updated… I've heard you can't convert to straight talk if your iphone has been updated, is this true? I can't find any info about it on the web… Need to know though… Also what does tethered mean, something to do with internet I know but can't you use internet on iphone anyways no matter what without a hot spot because it is on your plan because with the 45 dollar plan you get data so why would you have to be by a router or hot spot? Please help no nothing about switching to straight talk on iphone but want to… Thanks again in advance

Wi-Fi keeps dropping on my iPhone 4?

Nothing is wrong with my Wi-Fi but I'll constantly have to put my iPhone back on Wi-Fi about every 30 mins or less. Why? (And this is being in the same spot, my house. )