In slide mode, only the master slide and the current slide are visible. All other slides (layers) are hidden. To select objects on multiple slides:
1- Change to Layers
2- Select the Layers command. You'll see that only two layers are visible, the current and the master slide layer.
3- Show (unhide) all hidden layers:
- (MacDraw Pro) In the Layers dialog, Select All (Command-A), then click Show, then click OK.
- (MacDraw II) In the Layers dialog, click Show All, then click OK.
4- To select all text objects, click the text tool, then press Command-Shift-A
(or, turn on Multi-Layer Selection in Preferences, then press Command-A (Select All)
5- Make changes as needed
6- When done, choose Turn Slides On to return to slides mode.