you must do it yourself!
You can read this thread and adapt then your program.
If the problem persists in your site, you could describe your system as exact as possible, what you did, perhaps with printscreens of your settings.
PHP 7.2.9 on different sites
JEM 2.3.0dev 2.0M and specials with Joomla! 3.9.3 stable on livesites
ja_simply, ja_purity_iii, multilingual DE EN IT FR