You more than likely are using another mod that adds a minimap, most likely Hosav's UI and simply see that one behind mine now that I made the default settings so it's not 100% solid.

If that's the case you can just turn off Hosav's minimap by opening your inventory and clicking the white UI settings button to the left of your shortcut bar on the bottom, then scroll down in the settings that open to Minimap and remove the checkbox next to it so that it's disabled.

As for how you get to the Simple minimap settings, you just hold F1 on the game screen to get your mouse back and click the cogwheel on the border of the minimap. (You can also use the mouse to move it from the center point, or toggle it on / off from the hidden button on the top right corner of the screen - these are all shown in the demo video on the page here)

Thanks :)