[Koha] needed help in koha cataloguing module

[Zahid Iqbal]

Dear all,
i am using koha 22.11 version
i want to disable the indicator box and box for (a) (b) (c) etc so user can
not type and change the [a] [b] [c] to [e] [f] [3] etc. On adding/modifying
books koha page koha/cataloguing/addbiblio.pl when i click on 245 (*a*) it
allow me to change (*a*) i want to disable/readonly [a] and two boxes for
indicators so it cannot be changed.is there any system preference value to
restrict the user? or any other suggestion?
should i look into MARCOverlayRules ?
needed help in this problem.
Best regards,
-- 
*Zahid*