Which experiment design is this? Between and within combined
If I understand your description correctly, you have one within-subject factor with two levels (certain/uncertain) and one between-subject factor (based on how you assign the different text snippets to different group, but I'm not sure I understand what exactly you are doing there). So, this would be a repeated-measures design with different groups (based on the assignment of different text snippets) which I would refer to as is a mixed design (https://www.discoveringstatistics.com/statistics-hell-p/porus-comparing-means/mixed-designs/), and you could analyse it, e.g., with a mixed ANOVA (https://statistics.laerd.com/spss-tutorials/mixed-anova-using-spss-statistics.php). I think crossover-design refers to something similar.