Your "password repository" should of course be an
encrypted file, and so it's fine to keep it on "your account." In general, I recommend that you keep everything that "you" use on "your" account.
And – "your" account should be a
non-administrator account. (In Linux parlance, "
not a member of the
wheel group.")
Only one account should be "an administrator." (Don't name it "wheel" or "administrator" or "admin.") This is the account that you use for system administration, and
no other purpose. (Optionally, change the permissions on the user's home directory to exclude access from "others."
"-rwxrwx---" In case you want to store information there that is "nobody else's business.")
When you install Linux, it will create one "administrator" account. Immediately use this account to create other,
non-administrator, account(s) for your daily use.
The distinction of this particular user is not that it is "more or less secure," but "what it (alone!) can
do."
Only this user can "walk into a phone booth" and then
"fly(!) out."
Incidentally: this
principle of least privilege applies equally to
every(!) operating system: Windows, Linux, OS/X (MacOS). Because:
"computers are terrible at knowing when to say 'yes,' but terrific at saying 'no!'" Every OS provides its own (different ...) way of accomplishing this critically important distinction.