When I buy BTC from someone, how much can they see...?

[Bluehouse]

I've been buying BTC from someone over a longer term (a year or so) as I can afford it, and the other day they said that I have $2,000 in my wallet (which was correct).   This shocked me, the only thing I ever gave him was an address to send it to, and he's been using the same one the whole time. 

Can he keep seeing my balance?

Can he (or anyone) see when I spend it? 

Can he (or anyone) here I spend it, as in who gets it from me...?

And when I'm ready, what can I do so that my balance and habits are no longer able to be tracked by him?

Thanks in advance for your time.

[BestWebCreator]

Bitcoin runs on a public blockchain. People will always be able to track your address.

[Oceat]

Perhaps you should read more about blockchain.
https://en.wikipedia.org/wiki/Blockchain#Types_of_blockchains

I can't believe you were trading for a whole year with him with the same address and yet you never know any of this. People can totally track your transactions just putting the address on the search bar, easy peasy. No need for an exploits to do it because it is public.

[Bluehouse]

Bitcoin runs on a public blockchain. People will always be able to track your address.

But when I send the money to my cousin's wallet, can they follow it there, or can they just see how much I have at any given moment?

[BestWebCreator]

Bitcoin runs on a public blockchain. People will always be able to track your address.

But when I send the money to my cousin's wallet, can they follow it there, or can they just see how much I have at any given moment?

Everyone can see how much bitcoin every address owns at any given time. If you send from A to B, this will reflect on the blockchain and this will be trackable. People will not know the identity (name etc.) of the address owner, unless u have written it somewhere online and ur name can be connected to the address.

[gentlemand]

If you don't want people to follow your transactions all the way the quickest way is to deposit to an exchange and then withdraw. Obviously only do this to a totally legit exchange. The BTC will arrive in one address. You'll be paid out from a completely different unrelated address which gives you a new trail.

That's enough to stop people who have linked your address to you keeping track of where you're sending.

[exstasie]

I've been buying BTC from someone over a longer term (a year or so) as I can afford it, and the other day they said that I have $2,000 in my wallet (which was correct).   This shocked me, the only thing I ever gave him was an address to send it to, and he's been using the same one the whole time. 

Can he keep seeing my balance?

Can he (or anyone) see when I spend it? 

Can he (or anyone) here I spend it, as in who gets it from me...?

And when I'm ready, what can I do so that my balance and habits are no longer able to be tracked by him?

Thanks in advance for your time.

Use a new, unused address for every transaction. This way, the counterparty is only aware of that address, rather than all of your activity. This is the proper way to use Bitcoin for both privacy and security reasons.

In terms of security, your private key becomes easier to theoretically crack (like with quantum computers) once you spend from it because it exposes your public key.

But when I send the money to my cousin's wallet, can they follow it there, or can they just see how much I have at any given moment?

They can only see how much is in any given address at any given moment. Whether they can associate any given address with you is up to you and your privacy habits.

[joniboini]

But when I send the money to my cousin's wallet, can they follow it there, or can they just see how much I have at any given moment?

You can use bitcoin mixer to hide your original address when you send the money to your cousin. Add this with always use a new address to receive transaction, and this should make people won't know how much you own (unless they know the other address owned by you).