Is it mandatory to use a new change address each time for a bitcoin transaction?

Question

Computer networks

I got a little confused, somewhere they write that during the transaction your old address has already appeared on the network, and in the wallet settings you need to check the box "use the change address", in which the balance is transferred to the new address. The question is what does it mean to light up? Is the private key sent during the transaction?
Does repeated use of the same address lead to compromise? Is it safe?

Answer 1

The wallet address with the balance will be in the same transaction. Why do this - to slightly complicate the construction of a network of departures and receipts (instead of a "star" topology there will be a "tree", but one way or another it is easily processed), if you want to compromise this will not save.
The only way I know of to anonymously hold bitcoins or other cryptocurrencies is through storage on exchanges or in altcoins.

Answer 2

Here is a quote from one article that confused me (see the last sentence).
"A paper wallet is perhaps one of the simplest and most popular cold storage methods. Creating such a wallet involves generating a bitcoin address and secret key offline, and writing them to any medium that is not accessible from the Internet. For example, you can record a pair keys on a piece of paper, which you then put in your own safe or safe deposit box.You can send bitcoins to this address without any problems, where they will be completely safe.When you decide to spend bitcoins from the above address, you only need to import the secret key into the wallet program you are using.After this operation, your storage will turn from cold to hot.
If you need to spend only part of the accumulated funds, and keep the rest in cold storage, then after importing the secret key into the hot wallet, you should immediately send the rest of the funds to the freshly created cold wallet (your old storage has already been exposed on the network, and therefore can be compromised )."