Please help!

Every time I customize and add command button to excel 'standard toolbar',
it goes back to the default buttons when I open excel later. However, in the
'formatting toolbar' all the customized buttons get saved, so when I open
excel later, I have the customized 'formatting toolbar'.

How can I customize 'standard toolbar' and save so that I will not loose the
added command buttons when I open excel later?
Thanks in advance. TD