@mwdake: Sorry , I use 1:2 dilution at the moment. I will try a higher dilution as well as adding the potassium bromide. Thank you for your detailed recommendation.
@winger: Thank you for your recommendation. I will see if a different dilution helps me as suggested by mwdake, but otherwise will see if the multigrade developer works better for me. You are definitely right that liquid developer is much more convenient.
@Lopaka: Thank you for your recommendation. I will try and find some images developed with the warm tone developer and see if I will like it.