Also Create For: for Fields that already exist

Also Create For: for Fields that already exist

We are wanting to change a function of the field "Lead Source", which I believe was a standard option (not custom that we created ourselves), which came with our ZOHO account. Since there was no way for us to click the "also create for: accounts" button when making the field, is there any way to change that now so that we see the "Lead Source" in Leads as well as Accounts?