In WordPress, you can normally change the website logo from the Customize menu (Appearance -> Customize). However, this method doesn’t always work, depending on the theme you use. Some WordPress themes, such as Newspaper, come with a theme panel to customize your website. You can change the logo from this panel. What about Monstroid2?
Monstroid2 is an Elementor-based WordPress theme. Most components of this theme are built with Elementor. On Monstroid2, you can’t change the site logo from the Customize menu. This theme also doesn’t have a theme panel to customize your website. So, how to change the website logo on Monstroid2?
You can change your website logo on Monstroid2 from its library manager. You will see several templates on the library manager of Monstroid2 after you have installed a skin, including a header template where your site logo in. Go to Monstroid2 -> My Library to open the library manager.

Hover your mouse over the active header template and click Edit with Elementor to edit the template with Elementor.

On the Elementor editor, click the site logo (this is a Site Logo widget) to turn it into an editing mode. Select the website logo you want to use by clicking the image selector on the left panel.

Update the template by clicking the UPDATE button on the bottom side on the left panel to apply your new logo.
It’s crucial to note that Monstroid2 offers no option to resize the logo. So, make sure you upload a logo with a proper size. The logo size on Monstroid2 is varied, depending on the skin you use. Before creating your own logo, you can check the size (dimension) of the logo on the skin you use first.