Wordpress cannot change default size of featured image

Question

On my blog I want to add an ability to attach featured images to posts. However those images by default are extremely small (150x150px) also wordpress automatically compress the size of them.

I tried to set a larger size two ways: in settings->media I changed size of thumbnails to 750x550px also in functions.php added this code:

add_theme_support( 'post-thumbnails' );
set_post_thumbnail_size( 750, 550, true );

But it change nothing and I still get 150x150px images. How can I fix it?

I use wordpress version 4.9.4

Answer 1

Wordpress doesn't alter thumbnails of existing images in your media after changing the settings. You can use this plugin to regenerate thumbnails of your existing images : Wordpress Regenerate Thumbnails Plugin