The default Macro button icon in Excel Ribbon is shown in below image.
If there are too many Macros added to a Group in Excel Ribbon, it will become difficult to identify the Macro which you are looking for.
You may change the default icon used for your Macro button in Excel Ribbon by following below steps.
Step 1 - Right-click anywhere on Excel Ribbon and then select "Customize the Ribbon", as shown in below image.
"Excel Options" window is opened and its "Customize Ribbon" Panel is displayed as shown below.
"Excel Options" window to customize Excel Ribbon can be opened by following methods also.
• Click the "File" tab in Excel Ribbon and then click "Options". Select "Customize Ribbon" Panel.
• Right-click anywhere on the "Quick Access Toolbar" (except on "Customize Quick Access Toolbar" drop-down button). Click "Customize Ribbon".
Step 2 - Select the Macro which you want to change the icon from right-side list. Click "Rename" Button.
Step 3 - In "Rename" dialog box, select the icon you want to use for Macro from "Symbol" as shown in below image. You can choose a relevant icon for your Macro button from a variety of icons from "Rename" dialog box, as shown in below image. Click "OK" to change the Macro button icon.
Step 4 - Verify whether the icon is changed for the Macro in right-side list of "Excel Options". Click "OK" Button to finish, as shown in below image.
The default icon is changed and newly selected icon is assiged to the Macro in Excel Ribbon, as shown in below image.
Click the following link to learn How to add a Macro to Excel Ribbon.