Tried changing the directory name in the settings and got the following console messages:
Foundry VTT | Error thrown in hooked function '' for hook 'renderSettingsConfig' foundry.js:727:15
Foundry VTT | Error thrown in hooked function '' for hook 'renderSettingsConfig' foundry.js:727:15
Directory npc-portraits does not exist or is not accessible in this storage location foundry.js:58526:78
The form field value "[forgevtt] npcs" was not able to be cast to the requested data type Directory