Hi @Brownfield, Pamela,
Are you using the modern or classic view? If you are using classic view then you can do using a small jquery function as shown below:
$("#ctl00_ctl34_g_119225bf_8f0a_48d3_b96a_5e8213e30238_ctl00_toolBarTbl_RightRptControls_ctl00_ctl00_diidIOSaveItem").value="Submit";
If modern then you can do using powerapps. You don't have to change anything in your list just customize the form using the Power-apps from the option below.
Here is the document for reference
https://learn.microsoft.com/en-us/power-apps/maker/canvas-apps/customize-list-form
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.