If you are having trouble selecting shapes on your Visio drawing page, the problem might be that the shapes are protected or might be a part of a locked layer, or that they are grouped together.
Are the shapes protected?
If you can’t select a shape, the shape might be protected against selection, which prevents you from deleting or applying any changes to it such as positioning, resizing, formatting, editing text, or rotating.
(The following procedure requires the Developer tab to be visible on the toolbar ribbon. If you need help turning on the Developer tab, see Show the Developer tab.)
To unlock a shape:
On the Developer tab, select Drawing Explorer.
In the Drawing Explorer tree menu, right-click the drawing file name, and then click Protect Document.
In the Protect Document dialog box, clear the Shapes check box, and then click OK.
If you can select a shape, but can't apply any changes to it, the shape might still be protected. If grey handle bars appear on the shape you select, the shape is locked against all changes. In this case you will have to unlock all shapes from selection. To do that, see the section Lock or unlock shapes from selection in Prevent or allow changes to shapes.
Are the shapes part of a locked layer?
If you can't select a shape, it might be a part of a locked layer.
To unlock a layer:
On the Home tab, in the Editing group, click Layers, and then click Layer Properties.
In Layer Properties, in the Lock column, clear the check box associated with the type of shape that you want to select.
Are the shapes grouped?
If you can select the shape, but you can't work with it as you expect, the shape might be part of a group. Shapes that are grouped together function as one unit. For example, if the shapes are grouped, you can change their color at the same time.
To find out if a shape is in a group:
Simply click the shape. If the shape is in a group, the group will be selected instead of the shape. Now click the shape again, and that selects the shape in the group.
To select a shape within a group:
There are several methods of selecting shapes. For more information, see Shape selection tools.