For the most part, column width depends on the largest width of data in a given view of the records. In a table or datasheet view, double click the column separator and you'll get the width needed for that view. Scroll down and you may find a record where the data exceeds the width that was just set. Double click separator again and the column will get wider. AFAIK when your form opens the widths will be governed by the width of the data in the view even if you use the suggested setting. If you want to make it static, you can use the column width property in the form load event. I believe the value needs to be in Twips (appx. 1440 per inch).
EDIT - I believe you can also set the column width in form view and save the form and it will re-open with those settings. However, this won't prevent anyone from altering the widths and saving, so a code solution is probably the only way to make it permanent.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.