If you have changed the alignment and you cannot see the whole label, click on the bottom of the graph, hold down the mouse and pull down gently .  This way you make more room for the labels.

 
When adding numbers to a datasheet, do not leave spaces or add in any commas to seperate digits.  If there are thousands in the number then Word 'knows' what to do to show the large number. If you add in commas, for example, Word will see the data as text and will therefore not be able to do any calculations with the data.

 
If it appears that you do not have enough space to fill in the whole label in the datasheet, do not worry.  Stay in the same cell, just make the column wider by placing your mouse between the two affected columns and then click and drag to teh reuired length.