You should not do it via services console. SharePoint Timer Service should run under the farm admin account. If you want to update the password for it then
- Go to Central admin > Security > Configure Managed Accounts
- On this page click on the account and update the password.
If you want to change the farm admin account then follow the below stsadm command.
stsadm.exe -o updatefarmcredentials -userlogin DOMAINusername -password password
Or try to login with the farm admin account then try to change the Sharepoint timer service under your farm admin account. as it is only running under local account on one server out of 3.