The default powerpoint template almost certainly is not what you want to use. But it is easy to make a new default template to suit your needs. Here is how…
Open a blank template. The first thing I usually do is to set the default font to be Arial, which I prefer to the current Calibri font. On the menu, choose View|Slide Master. At the left, choose the first of the page templates. Click back on the slide template. Select all (Ctrl-A). On the Home tab, choose your font (eg Arial) – don’t set the size, as these vary depending on where in the template you are – it usually is not ideal to make all elements the same font size. This sets Arial as the default text for all the template default page elements.
Return to normal view (View | Normal).
Now you might want to set the defaults for text boxes etc. So make a text box. left click the border to select the box. Choose the font. Change any other text box settings you want. Right click the border and select “Set as default text box”. Delete the text box. You should now have a blank slide (Plus or minus the heading / subheading boxes, depending on whether you deleted them or not).
Now save the template as your default. File | Save as | select ‘PowerPoint Template (potx); The file browser area will select the relevant area. Enter Blank as file name. click save. (overwrite an existing file if it exists)
Now, when you open powerpoint, the settings you made will be the defaults.
Happy slide making.