ds(5) has started being quite cheeky and saying 'no' when told to behave. and when i ask him to do something, like change into his pyjamas or tidy his toys, he will sit silently until i ask him again and will only do it if i threaten to confiscate a toy. sometimes even then he refuses and i follow through with confiscation and he will throw a tantrum. i have started telling him, "i will only ask you once to change into your jammies. if you don't do it when i ask you will lose a toy/priviledge" but it doesn't work.
how can i get him to stop the 'no' answering back and to do as he is told without the constant warnings and threats?