How can I keep the relative position of the stimuli when switching to a different screen size?

[wakecarter]

Use height units to maintain aspect ratios and relative distances.

Use norm units to fill the screen or keep things in the corners from getting hidden.

Aspect ratio of rectangle used by text components

I think the issue is that you have switched from norm to height units without realising. The screen is 2 norm units high but only 1 height unit. The screen is 2 norm units wide but could be between 1.333 and 1.778 height units wide. Yours is the latter. For text components I often go back to norm units. Height units are better for stimuli since they are the same size vertically and horizontally. You can set the wrap width of a text component on the advanced tab. I often use 1.5 norm units.