Bookmark them in Tor Browser. Now you don't have to remember them; just start typing the name of the website.

Here's a tad inconvenient method of securing sensitive files I just thought of:

• Keep a plaintext file with the info on a tmpfs (/tmp/)-- it'll be killed after rebooting your PC.
• Better yet, set /tmp/ to be hosted only on memory (some systems have this as default, others just remove /tmp/* as a part of startup).
• When you have to reboot and you don't want to lose the sensitive files, use scp to transfer them to the /tmp/ dir of a second PC on your network.
• When the first computer's done rebooting, scp the file from the second PC's /tmp/ to the /tmp/ of the first PC.
• It's most convenient to have a shell script automatically scp the file back-and-forth-- it leaves a trace of the filename, but not what's in it, so it's probably fine.
• You might want to encrypt the file for extra security, if you're really paranoid. It's probably fine, though.

Some downsides to this:

• Even if the file's just in memory, it leaves traces. I don't know enough about these traces to tell you how to reliably get rid of them (aside from filling up memory [which ought to be enough?] or snapping the RAM in half or something), sorry. Better than using HDD, though.
• If the power goes out or you accidentally power off both PCs... your file is basically gone. Whoops. Cross your fingers that doesn't happen.

Personally, I use keepass. That way, I have a number of different, complex passwords that I don't need to remember, a single complex password that I do remember, and a list of bookmarks that doesn't disappear every time I update the tor browser.