I recycle old envelopes by using the plain backs like index cards.
Each one is titled then a list, e.g.,
ME ONLINE FORUMS
ME/MEW(G-1) followed by the password
Followed by other forums
The (G-1) tells me that it's on my no. 1 Google account
So many sites needing passwords and other security info., I had to devise a way of classifying them in different lists to find details when needed. I found this works quite well. Passwords get change frequently. That fills up space so start new envelope list and shred old one.
Another list is titled ME. SUPPLIERS and lists quite a few like Arceuro, Maccmodels, The Tap & Die Co. Includes "The Nut & Bolt Store" as it's a handy local (Hove) emporium, giving their opening times.
Another list headed "Internet Traders" for miscellaneous sites like Giffgaff, Cheap Energy Club, MSE(Martin Lewis), Abebooks, Paramo(outdoor clothing), The RAC, Hove Polyclinic phone no.
Yet another is ME CLUBS for my membership info.
Several more lists, all of which helps me to find which Google or Yahoo account used to access my account and the password. Some cards like financial lack passwords and other vital info just in case of burglary. In fact most passwords have missing characters which I can remember to insert when used. Don't use social media so that much harder for scammers. Still get occasional emails and texts trying to catch me out like the recent one to pay £1.45 before parcel is delivered under threat of returning it on non-payment. As I delete it laughing and commenting well send it back then, ha,ha.
Hope the above may be of help to sort out an untidy muddle of sites and forums and which email address and keeping tabs on passwords.
John