You can do this by editing the style.
1. Remember to take a backup of the files you are going to edit before any update.
2. Login to the admin dashboard.
3. Navigate to Appearance->Editor and select Stylesheet (style.css)
4. Now add the following style:
.menu ul li ul{display:none; left:0; top:0;} .menu ul li {position:relative;} .menu ul li:hover ul {display:block;}
5. Update the file.