The activity upload icons can be overridden in the theme.

Default activity upload icons:-

New activity upload icons:-

Steps to override the default icon with your own:-

It’s important to understand how template/asset overriding works in MediaPress. You copy a file from plugins/mediapress/templates/mediapress/default/abc/somefile.php and put it in your themes/your-active-theme/mediapress/default/abc/somefile.php

Ex:- 

plugin/mediapress/templates/mediapress/default/somepath/somefile.php -> themes/current-active-theme/mediapress/default/somepath/somefile.php

Effectively, Anything that comes under mediapress/templates goes to the root of the current active theme and you maintain the file hierarchy.

Since override is allowed for the upload icons, we can replace them in our theme.

Here is screenshot showing the default icons in MediaPress plugin(note the path relative to the mediapress/templates directory)

And we maintain same hierarchy in our theme and replace the icons(again note the path relative to the current theme )

Now, That’s easy. Here is what we get.