@Megin_Murphy, there are a couple of ways to do this. One way is with the base open, click on the little drop-down arrow next to the right side of the name of your base which appears at the top… You will see the name of the base highlighted and that field is editable. So, just change it (type over) there and you are done.
Also, notice in this same drop-down menu, you can change the color of both the base icon and overall look; you can also change the icon itself. Note that the icon choices have a little scroll bar on the right to scroll through a long list of possible choices other than those that are seen initially. There’s in addition a number of other menu choices below you can choose including the sharing options.
Hope that helps.
