If you want to use default header bar instead of custom header bars or one of predefined header bars built with WPBakery Page Builder (formerly: Visual Composer), then you can change your logo image in Theme Options page.
Where to change logo for default header bar?
Login to your WordPress admin panel, and go to “Ueldo” – “Theme Options” page. Find “Header” option and upload your new logo image there.
If you want to use second header bar (flying), and it also will be the “default” header bar, then you can change its logo image in the same place (you’ll see different field for that below).
Recommended logo dimensions
Logo image which will be used in default header bar will fit automatically to the header height. Maximum height of logo image is 74px – if you’ll use bigger image, then it will be scaled to this size.