To raise own key trust level:
$ gpg --edit-key user@example.com Secret key is available. sec rsa3072/XXXXXXXXXXX created: XXXX-XX-XX expires: XXXX-XX-XX usage: SC trust: unknown validity: unknown ssb rsa3072/XXXXXXX created: XXXX-XX-XX expires: XXXX-XX-XX usage: E [ unknown] (1). User <user@example.com>
gpg> trust
sec rsa3072/XXXXXXXXXXX
created: XXXX-XX-XX expires: XXXX-XX-XX usage: SC
trust: unknown validity: unknown
ssb rsa3072/XXXXXXX
created: XXXX-XX-XX expires: XXXX-XX-XX usage: E
[ unknown] (1). User <user@example.com>
Please decide how far you trust this user to correctly verify other users' keys
(by looking at passports, checking fingerprints from different sources, etc.)
1 = I don't know or won't say
2 = I do NOT trust
3 = I trust marginally
4 = I trust fully
5 = I trust ultimately
m = back to the main menu
Your decision? 5 Do you really want to set this key to ultimate trust? (y/N) y
sec rsa3072/XXXXXXXXXXX
created: XXXX-XX-XX expires: XXXX-XX-XX usage: SC
trust: ultimate validity: unknown
ssb rsa3072/XXXXXXX
created: XXXX-XX-XX expires: XXXX-XX-XX usage: E
[ unknown] (1). User <user@example.com>
Please note that the shown key validity is not necessarily correct
unless you restart the program.
gpg>
CTRL+D