You could create an encrypted volume with VeraCrypt which is open source, and store your notes and other sensitive documents inside. It's convenient because you can mount the volume when you need to access it and then unmount when you want to lock it. The volume is encrypted and password protected. With VeraCrypt you can create hidden volumes which give you plausible deniability, you might want to consider this if it's something sensible for your threat model.
Tails lets you create "persistent storage" which is an encrypted partition protected by a password. You can just store your sensitive files including notes in there.
VeraCrypt is a good choice but I'm not sure if makes sense to use it on Tails as it already offers persistent storage which is secure and easy to access, I would just go with that. I use VeraCrypt on my Linux desktop to store any personal files securely.
VeraCrypt is a good choice but I'm not sure if makes sense to use it on Tails as it already offers persistent storage which is secure and easy to access, I would just go with that. I use VeraCrypt on my Linux desktop to store any personal files securely.