[Plugin: My Post Order] Increase Number of Posts that can be sorted

If you want to sort your posts, then there is no such limit. Once you check ‘Want to reorder’ option, selection box of number of posts will disappear.

If you don’t want to sort, then you need to open includes/defines.php. There around line no 10 you can see define('DEFAULT_NUM_POSTS', 20);

You can change this 20 to 50.