To more easily align objects on a slide in PowerPoint for macOS, you can snap your objects to vertical and horizontal guidelines that run through the slide. You can also use dynamic guides—guidelines that run through the center of other objects and the center of the slide and appear when you drag an object—to align an object relative to another object.
Turn snap to grid on or off
Click View > Guides > Snap to Grid.
Turn dynamic guides on or off
Click View > Guides > Dynamic Guides.
Tip: For fine control over placement of objects on a slide, hold down Command while dragging.
Add or remove guides
Drawing guides can help you position shapes and objects on slides. Drawing guides can be shown or hidden, and you can add or delete them. When you drag a guide, the distance to the center of the slide is shown next to the pointer. Drawing guides are not visible during a slide show and do not print in a presentation.
(This information about adding/removing guides doesn't apply to PowerPoint for Mac 2011.)
To show or hide guides, select Guides on the View tab.
To add a guide, Ctrl+click or right-click on your slide, point to Guides, and then click Add Vertical Guide or Add Horizontal Guide.
To remove a guide, Ctrl+click or right-click the guide line, and then click Delete on the menu.
You can change the color of a guide, allowing you to use colors to denote different meanings or just make a guide stand out from the background. Right-click the guide, select Color, and make your selection. (This feature is available in PowerPoint 2019 for Mac and PowerPoint for Office 365 for Mac.)