it's not really an import. when you first start the current return, you should be asked about transferring the prior year's data to which you should agree. you have to be in the same account that you used for the prior year. if you don't transfer before starting the return it's too late. importing will not work. the return would have to be deleted and you would need to restart the process.
if you are getting this message about the file being too large when you try to transfer contact support.
