If you have a certain fill or line that you would like for all the shapes that you draw in the current presentation, you can set that formatting as the default for new objects. Create a drawing object and format it the way you want. The right-click the object and choose Set as Default Shape.
Text boxes work similarly
To set the default for text in text boxes, you need to use a different method. Click anywhere on your background or off the slide to make sure that no objects are selected. Then use the Format menu to make the desired settings. For example, you can set the alignment (left, centered, etc.) and the font style (for example, italic). Then right-click and choose Set as Default Text Box. Now, if you create a text box, the text will follow these defaults. These settings don’t affect text in title and body text placeholders which are controlled by the slide master.
To make these settings stick, save a template or theme and use that the next time you open a presentation.