I see several times in this thread that I should "change addresses every time I make a transaction". Does this mean that I should use a new address when I RECEIVE coins to my wallet? Because the receiver when I send will always see how mutch btc there is in the wallet no matter how I do with new addresses?
If you are using a good wallet, it has the option to create a new address. You should create a new one fore every transaction. Nobody knows what addresses do you own. However, if you use only one, the people you trnasact with will know how many bitcoin you have.
If you have many addresses, the people you transact with will know only the balance of the address you give them.
Another good option is to send the coins to a mixer to make it more anonymous.
But I'm a bit unsure of this alternative because I want to have the option in the future to show that I sent that coin from A -> B (I own wallet A and B). With a mixer it will be A -> "mixer" -> B and can I show any prof that the transaction from the mixer original was "my coins"? Say if eg. the IRS want me to explain all of it and they only see a transaction from the mixer -> B and that they don't belive that it only was a transaction from A. Perhaps a bad example but I hope you got the point of maybe avoiding a mixer..
This is the best option.
Mixer will not do A > mixer > B.
The mixer will do dozens, maybe hundreds of transactions with your coins, and will give you other coins (which are not yours). Look at this image, for example
if you send a mixer 1 btc, you will probably receive about 10 addresses (at least) with funds. You can read more about a good mixer here:
https://chipmixer.se/faqChipMixer creates Bitcoin addresses and funds them with specific sizes. These are chips with 0.001 BTC, 0.002 BTC, 0.004 BTC and so on till 4.096 BTC. When you deposit your Bitcoins, you receive same amount in chips. For example you deposit 0.112 BTC and you receive 0.064 + 0.032 + 0.016 chips. Each chip was funded before your deposit, so there is no link between them and your deposit on blockchain. They are already anonymous.
Never said that in the first post but if I sell my coins to fiat it will only be on a KYC exchanges (even so, I don't want them to see how many coins I have). Or if I buy something with my coins, I dont wan't them to see how mutch coins I have or give them the ability to follow the transaction to the wallet I have now with all my coins. It's the reason why I think it will be a good option to bounce it to a non KYC exchange.
If you want to trade for Fiat, just look for a good exchange, do your KYC and sell it. It is the safer way. You would still need to pay taxes. There is no way to make money legally without telling the government. You should do everything in a legal way.