Do we have to file same ITR form for each year

Hi,

I filed ITR 3 last year as I was having salary as well as income from share market trading. But this year I am only having a salary income and do not have income from the share market. So should I file ITR 3 even this year or can I file ITR 1? Also, in ITR 3, the salary income section is not prefilled as in ITR 1.

 Please guide me on this. Thank you