After take-off always nose up attitude??

Hi
After taking off my plane always seems to have a nose up attitude. I always have to put nose down trim, but it keeps going back up. This happens with the Dash8 & my B1900. I am constantly pushing forward on the yoke just to keep it level. 🙄
I also reduce the throttles after take off. Any ideas to keep myself level?

Thx, Tom