Grid bubble
A grid bubble is, like so much else in Revit, a family
If you look at the type properties of your grid you will see that it uses a family for the grid symbol.
You can choose a different one.
If there is only one option you can create a new grid head family with the shape desired, load it into your project and than choose it in the type properties of your grid
Louis
Please mention Revit version, especially when uploading Revit files.
Accepted solution