How to import keys in ZCASH

I have used JAXX for a while to receive my mined ZEC (once a day or so), but now it started missing transactions (=payments) and Jaxx’s customer service told me is not good for continuous micro payments. I downloaded the official app but when I try to import my Keyes it requires a complex TXT file (I exported keys to see the template)… while I only have 3 private keys I would like to enter in some way. How can I do so?