Changing label of assignment on Moddle 2.5

Hi everyone, I have a doubt, I can modify the label of the assignment 2.2, but not completely as I want, I explaint it (see atachment), I can change the label and write a point instead of the text, but the alignment is not what I want nether the icon on comparison of the rest of activities. The action works on the radio button next to the label; thus, I would like to change the icon of the hand by a personalized icon.

Besides, I would like to know how I can modify the code of the php file.

Can someone help with this problem?

Thanks for your support.

Note: I am working on moddle 2.5