Hey Rudy. I'm Greg, an installation specialist and 8 year Windows MVP, here to help you.
What I've always done with no problems is install 7Zip, in File Manager choose the file you want to password, then Add to Archive, it will open a box where you can provide a password and/or zip the file up more if you want. Save that and test opening the new 7zip file to see that password works. If so delete the original.
I hope this helps. Feel free to ask back any questions and let us know how it goes. I will keep working with you until it's resolved.