I have this old account that is converted from eth when eos was first sold, I'm only to trying to use it now, but I just found that it only leaves 10eos as unstaked, while all other tokens are stacked, half into CPU, half into NET, I don't remember I have chosen to stake this, also I don't find any interests generated for my staking, did I do something wrong?
Staking EOS doesn't give you any interest. It provides resources (CPU/NET) for sending transaction and the power to vote producer.
If you delegate your voting power to proxy like this, they will give you reward. There are many proxies, so you need to compare them by yourself.