My advice is always to copy and paste important passwords from a text file and then to encrypt this text file, copy it on a removable device ( external HDD, USB stick, etc. ) and lastly erase it from the HD.
That's exactly what I do: cut and paste never type. Except I use an encrypted Excel file not a text file. I once almost got into trouble when Microsoft used to encrypt Excel (over 10 years ago) with a certificate that resided in your hard drive, and then, when I took my Excel file to another PC far away, running the same version of Office, I could not open the file since the root certificate was different. Luckily I was able to get a trusted friend to decrypt the Excel file on my original machine and send it to me. Microsoft has since fixed this bug and apparently Excel's encryption is supposedly pretty good now, unlike the way it was over 10 years ago.