You can use the script below where you can identify the targeted column using the number.

 

In the example below

• Change (3), in the script to target the column you want to update
• The column name is being changed to "New Text."

1. Access the Custom styles via the webpart settings:
   
2. Paste and adjust this script to your liking:
   

   table.kw-Table--selectable th:nth-of-type(3) {
    vertical-align: top; /* align cell content to top */
    position: relative;  /* required for absolute children if needed */
   }
   
   table.kw-Table--selectable th:nth-of-type(3) span {
    visibility: hidden; /* hides the old text */
    position: relative;
    display: inline-block;
    height: 100%;
    vertical-align: top;
   }
   
   table.kw-Table--selectable th:nth-of-type(3) span::after {
    content: "New Text";
    visibility: visible;
    position: absolute;
    top: 0;
    left: 0;
    white-space: nowrap;
   }