Hi Abhishek,
you can change mendix logo from layout
Go to Marketplace module—>Atlas_Core->Web->Responsive->Layout->Select your layout(Atlas_Default) here you can change your logo.
Hi Abishek,
Depends a bit on what your page setup is, but most of the time you can change this in the Layout of the page.
When your on a page you can see in the properties the name of the layout(probably atlas_default or atlas_topbar).
If you navigate to this, there you can change the logo.
Attaching snip for reference.
You can use Mendix studio if it is your own project and make changes quickly or create a layout for your home page. And then change atlas default layout to your layout from the home page settings. https://docs.mendix.com/refguide/layout/