Any way to change password on MyEtherWallet?
You cant. The password helps the website generate a private key for you. If you don't trust your account, create a new address and key and move your funds.
This is the only way to do it. If you feel the need to change your password because your ethereum wallet may be compromised, then you really should create a new wallet as soon as possible. If your problem is that you forgot your ethereum wallet password, then you may need to find your unencrypted private key to access your wallet again.