Copy Formula down to last cell in column

Hello,
I am working on an excel sheet for Incident Tracking, There are two columns in the sheet that have formulas (different formulas), one for generating unique ID number [IF(COUNTA(B2:Q2)>0,"INT-" & ROW(B2)-1,"")] and the other one is to workout the difference between two dates [NETWORKDAYS(B2,D2)].

Now my problem is when I typed in the formulas in the formula bar for each cell, the formulas are not copied automatically to the next row. I have to type them again in the cells, or copy and paste the formula then change the row numbers. How can I automatically make one formula copied to the end of the column?

Since I am a beginner, could you please help me with different solutions to do this.

P.S: I searched in the website and there is one method I noticed to do that, which is Tools>Options>Extend forms and fomulas... But it didn't work for me and didn't copy any formulas.

Thanks
alrahbia

There are two types of cell referencing: absolute and relative. The kind you are using is relative and the row numbers will change when you copy/paste or autofill. By putting a U.S. dollor sign ($) before the row number: (B$2:Q$2) you will avoid this change. The same can be done for the column letters.