Display errors on the screen

During the use of the program I notice that before loading the pages red bars appear for a moment which most likely contain errors but which I cannot see because the requested page is loaded immediately. Where can I activate the debugging of errors to see them on the screen or in a file? No errors are reported in the apache log file.
Version OJS
php 7.4

You can change the following lines from the config file (off > on).


; Display a stack trace when a fatal error occurs.
; Note that this may expose private information and should be disabled
; for any production system.
show_stacktrace = Off

; Display an error message when something goes wrong.
display_errors = Off

; Display deprecation warnings
deprecation_warnings = Off

ok but putting them on I don’t understand where the errors are printed. On safe video no. Not even in the apache error log file.
I always see errors that appear for a moment on the screen but cannot be read because the requested page is loaded immediately