scart and hdmi wont override tv signal,and wont switch manually sometimes?

this is for my dad,hes just bought a new toshiba lcd hd tv,sorry dont know model yet :) but the problem is,the scart/hdmi inputs dont always pick up,and never override the freeview(if this makes sense) when he puts the dvd on or his bt vision box on it needs to be switched to this manually via the source button on his remote,sometimes this comes up with the input options,scart hdmi pc ect,but mostly doesnt,ive tried 3 scart leads,a hdmi cable and even the white,red,yellow leads,but same problem even when we get it on the hdmi for his bt box,once he turns tv off it reverts back to the built in freeview channels??? any ideas out there brainy people?