Importing old data

I let my Quicken account expire last year. I renewed it but I am missing data in my account for about a 3 month period (April to July 2018). I went to my credit card company, searched for all the data for that period and then download a QFX file. However when I went to import the data  Quicken forced me to import it into a new file, The "Link to an Existing Account" option is grayed out. I deactivate the account then reactivated it but that didn't make a difference. Is there a way to import old data into a Quicken account to fill in the gaps?