Seems you have chosen animations which are too long for your lines. Even if you should have manipulated offset, blend in/out, speed and weight - what you didn´t mention - a lot of the animations of the library are not really appropiate for the conversation editor.
You mentioned armscross ex, therefore I guess that you have selected animations from the general animation library via browse in the animation tab.
Use instead the poses in the cinematics tab. E.g. "Line 1: Default/ Standing neutral / left / right - Line 2: Arms crossed - Line 3: Arms crossed - Line 4: Default/ Standing neutral / left / right" will work fine.
Set a value in the field X-Delay if the start of the arms crossed pose should match a specific word of the line.
Additionally you can add animations in the animation tab. Stay with the options offered in the drop-down-menu. E.g weight shift animations or gestures in combination with default or neutral poses. E.g head movements with gesture poses.
You can even add automatically gestures (or poses) to the lines. (Right click on the root -> generate for children, right click on a line -> generate gestures for line) Remove gesture animations which possibly could be added by the option 'for children' to lines where you have already assigned a pose with gestures. The system isn´t smart; you should probably have an idea from the cutscene editor which type of animations can be combined and which not.