Thanks capezotte,
I create /home/${USER}/Documents/PDF
/home/${USER}/Documents/OCR
and edit these two files /etc/cups/cups-pdf.conf
/etc/cups/cups-ocr.conf
respectively as following:
Out /home/${USER}/Documents/PDF
Out /home/${USER}/Documents/OCR
the changes takes effect immediately.
Apparmor is already installed (I don't know why) and contains:
/etc/apparmor.d/mariadbd_akonadi
/etc/apparmor.d/mysqld_akonadi
/etc/apparmor.d/postgresql_akonadi
/etc/apparmor.d/usr.bin.akonadiserver
the service is not registered or started ```rc-status```
rc-update -v show
NetworkManager | default
acpid | default
agetty |
agetty.tty1 | default
agetty.tty2 | default
agetty.tty3 | default
agetty.tty4 | default
agetty.tty5 | default
agetty.tty6 | default
alsasound |
avahi-daemon | default
Anyway, the problem is solved, thanks again for your quick clarification.