In order to add or change your transition between slides you will need to do the following:
Go to the thumbnail pane and select PowerPoint slide where you want to add/change a transition. Note that your new transition will start on the proceeding ppt slide and will conclude on your selected ppt slide.
Go to the tab “Transitions” and pick up the most matching transition effect from the gallery.
In order to specify the way your transition will occur, you will need to press “Effect Options”.
This step is optional:
In order to set the speed of your transition, you will need to enter a time in the box “Duration” on PowerPoint Ribbon. If you want your transition to go a bit slower, you will need to set the higher number.
If you want your entire PowerPoint presentation to have the same transition, you will need to press “Apply To All”.
If you want to check how your transition looks like in action, you will need to select ppt slide which starts your transition and press the icon “Slide Show” in your browser window (see the lower-right corner).
Note tat this button will activate the mode “Slide Show” on the selected ppt slide, rather than the very beginning of your presentation.