Never reuse bitcoin addresses
It is terrible for your privacy.
If I use the same address for everything, all my transaction history is linked to 1 address.
Anyone with that address can see how much bitcoin I have, and every transaction I have ever made.
It is as simple as putting it in a block explorer:
Because people need your address to send you bitcoin, and you send people bitcoin FROM your address.
Every person you interact with can see your transaction history.
It is permanent and public.
Using a new address each time means you leak far less information.
Here is a fresh bitcoin address- no balance, no transaction history.
If you have questions, I may have already answered them in this Twitter thread: