How to change flowchart shapes in Excel
In Microsoft 365 in general and in Excel, you don't need to plan because you can easily change the shape outline at any stage.
To change flowchart shapes in Excel, do the following:
1. Select the shape you want to change:
2. On the Shape Format tab, in the Insert Shapes group, select the Edit Shape dropdown list:
3. In the Edit Shape list, select the Change Shape dropdown list and then choose the shape you prefer:
4. Change the format for the changed shape:
See also how to change format shapes in Excel.
See also this tip in French: Comment changer les formes de diagramme dans Excel.