Visual search task

Hello. Thank you for the availability of this useful platform. So I am building up an experiment on the builder that i then want to move online. It is a visual search task which involved the presentation of 8 different stimuli (i.e. jpg images of different fruits). In this task there are 7 distractors and 1 target. However, the target varies each time in the sense that the target will be an apple on 70% of the trials, an orange 20% of trials and a banana 10% of trials. The identity of the 3 different targets stays the same for every participant (for a specific subject, an apple will be the most frequently presented one, the orange the middle presented and the banana the least often presented). But this should vary between participants in the sense that while for one subject orange, apple and banana are the three possible targets, for another subject any other 3 (out of the 8) total images can be the targets. So what is a distractor fruit image for one participant might be a target fruit image for another. I hope that makes sense.

How could I do that on the Builder? I started trying out different things by importing creating a loop and importing an excel file but i do not know how to make the targets/distractors vary between subjects.

Thank you in advance