1. Get the saved information: First, you need to get the saved information from the database or other data sources, and determine the project to be specified at present.

2. Fill the first drop-down list box: According to the obtained information, you can determine the items that need to be selected by default in the first drop-down list box. You can use ASP's for loop statement to iterate through each option in the drop-down list box, find the item selected by default and select it.

3. Fill the second drop-down list box according to the options in the first drop-down list box: according to the items selected in the first drop-down list box, get the options to be displayed in the second drop-down list box and fill them in the second drop-down list box. You can also use the for loop statement to iterate through each option in the drop-down list box, find the item that needs to be selected by default and select it.

4. Fill the third drop-down list box according to the options in the second drop-down list box: according to the items selected in the second drop-down list box, get the options to be displayed in the third drop-down list box and fill them in the third drop-down list box. You can also use the for loop statement to iterate through each option in the drop-down list box, find the item that needs to be selected by default and select it.

Through the above steps, you can specify the current item in the list according to the existing information, and display the correct saved information when you enter editing again. It should be noted that if there are too many options in the first, second and third drop-down list boxes, using the for loop statement may affect the performance of the program, and the optimization scheme needs to be considered.