Change Button Label in Customer Accounts

Hi! 

On my website, I sell plugins for Final Cut Pro. Occasionally, I need to update these plugins. I created an FAQ and a guide so my customers know what to do: Log in to their accounts, go to orders, select the order and click on "Download Item" to give them the refreshed version of the plugin. So far, so good.

Now, a customer asked whether I could change the label of this button to "Update / Download Item" to clarify the process. Is that something I can do with custom code?

If so, can anyone help out? I have no experience with code except installing the occasional plugin.

Thank you in advance!