This is quite easy to do, as are all things, once you know what to do.
Go into the cPanel for your site and open up the File Manager. Double click on Public HTML, then look for a .php file called wp_config.
Normally, I would caution you to make and save a copy of the whole unedited file to your desktop before-hand and this is a good habit and practice to follow. However for something this simple I no longer do this myself. Yeah I probably should.
Right click on wp_config and open it for editing.
Now scroll down in the file until you find this line;
define('WP_DEBUG', false);
Directly under this line place the following line of code;
define('WP_MEMORY_LIMIT', '256M');
If you are using Elementor and unduly worried about setting this too high, reduce the number in this code to 128M. However, this is an unnecessary concern. I always use 256M, not because I am a rebel without a cause but because by using the higher number that site is now ready for WooCommerce in the future. No need to ever revisit this file to change it again.
Final most important step
Save the file.
That's it. You have just successfully increased your wp_memory_limit.