error importing database

Hi guys,
I got tired of my web hosting company so i tried to move my website to another, but i’ve got a problem with importing the database Error: “Unknown collation: ‘utf8mb4_unicode_ci” and else, so i searched and i found this https://wordpress.org/support/topic/sql-error-when-importing-database-1?replies=3, they say that the problem is in the sql version, i have no way to change that, so they say also to try and change “utf8mb4” to “utf8” so i did it and i finally uploaded successfully but i’ve got a problem with post-new.php it’s frozen i can do nothing, so..
please help