Yesterday 
Before going any further I would like to give a short description of what exactly is a recovery account. Basically, if your account gets compromised or if you miss your private keys, you will be able to recover your account back with new keys with the help of the account that you set as a recovery account.
Why is it important to change the recovery account?
There is a high possibility of a phishing attack on any of the accounts. Though we have a very good password for our steem account, there is a possibility that our account can get hacked. If something like that happens, the recovery account will help us regain control over our account with a simple recovery process. The account that we set as a recovery account will be able to recover our keys or reset out keys. Not just hackers it can even help if we misplace our master key somewhere.
You can either set a trusted account as your recovery account or even your alt account as a recovery account if you can do the recovery by yourself. There are steps and guides available to recover your account with the recovery account you set. A week back I wrote a post in detail about how you can use your alt account as the recovery account. You can check that post to get more information on the same.
How to change my recovery Account?
On steam, we had the option to update the recovery Account through Steemworld.org. There was a straight forward method to change the recovery account. But here on Hive, we don't have a tool similar to Steemworld but after the introduction of HiveSigner, we do have an option now to change the recovery account. The below link can be used to change your recovery account.
https://hivesigner.com/sign/change_recovery_account?new_recovery_account=esteemapp
You can actually set any of your alt accounts as your recovery account. The above link is an example to set esteemapp as your recovery account. If you would like to change it to anything else or your alt account, you can do so by changing the account value in the link.
How is the power-down period related to accounting recovery?
This has been a confusion for some of the users. You might get confused if I say that account recovery also plays a vital role when it comes to power down period. If an account is hacked and if the account owner decides to do a recovery, it can take some time for the recovery to processing. Steen used to take over a weeks time to recover an account. If the power-down period is reduced to 3 days or instant, there are many consequences and this is one among them. There is a high possibility that a hacker can run away with our money. After hacking the account, they can technically initiate a power down and get the money out soon.
That is one of the reasons why it makes sense to have a higher power down period. In case our account gets hacked, the hacker will not have access to our powered up funds. During the waiting period, we get options to do the recovery and safeguard our funds.