making the measures wider

Depending on the situation you are referring to you may do a few things.

Enter notes, the measure will become wider to accommodate them.

Do these if the notes are already entered:
If in page view select the measure and press the } (shift ]) key to increase measure stretch. You can also increase the stretch for measures around it to make MS change the layout until you are happy with it. This may not ever work depending on the measures affected.

If you are in page view, put a line break at the end of the measure, if the measure is the last one on the line put one in the measure before it so the measure will start a new line. You can then see if it is wide enough for you. If not and there are other measure on the line after it, put a line break somewhere on that line so fewer measures will be on the line.

Select the measure(s) you want to increase and use Layout / Increase Stretch. But don't do this until after you've entered all of the notes! Measures automatically space appropriately as you fill them in, and you don't want to mess that up beforehand.