How can I make seamless loops

I try to make seamless loops with Zyn and seq24. In seq 24 I did sequence lenght to 1 and I also made a note lenght with 1. Optically it seems, that the note lenght don´t reach the end of the bar. Is there a possibilty to write longer notes than 1? Another thing is, that I want to change Zyn during playing the loops, but it seems, that the changes get set when seq24 starts the new loop. Is there a possibility to get realtime change with Zyn? Thank you Rudl