There's no way to change the colour of the filter arrows.

If you can use programming, there's a sample file here in which the
heading cell is coloured if a filter is applied to that field:

http://www.contextures.com/excelfiles.html

Under Filters, look for 'Colour Filter Headings'

Or, without programming, you can colour all the headings if any column
in the table has been filtered. For example:

Select all the headings
Choose FormatConditional Formatting
From the first dropdown, choose Formula Is
In the formula box, type:
=COUNTA($A:$A)<SUBTOTAL(3,$A:$A)
Click the Format button
On the Patterns tab, select a colour
Click OK, click OK

sandro wrote:
I use filters in excel extensively, occasionally I do not realise I have a
filter on a worksheet as the dark blue filter arrows are not destinctive
enough to the black arrows when the filters are off. How do I change the
arrows to a brighter colour e.g red


--
Debra Dalgleish
Excel FAQ, Tips & Book List
http://www.contextures.com/tiptech.html