The data on the form or subform is being generated by a query. If you used the subform or form wizard to create the form then Access created that query.
You can view it by opening the form properites window (right click on the little box at the top left of the form, then select 'properties' at the bottom of the dialog box)
In the form properies window select the 'record source' field. At the right you will see a box with three dots, click this box and it will show you the query that generates this form.
At the top of this query you will see a drop down box that has the work 'All' in it, this means that all records generated by the query will be displayed. You can use the are to select select from the values in the dropdown box "5, 25, 100, etc".
Or in the SQL view you can add 'TOP XXX' after the word 'Select'. Where 'XXX' equals the number of records you would like to select.
You mentioned that you would like the three most recent "colours", this would be depend on the date the records were entered and you would have to sort the query by the date in desending order.
Hope you can understand all this, I am having the same kind of problem but I would like user to enter how many records should be displayed.
MTmace