I've already done that, but I don't know how to program the number of times I want each word to appear (one in the first block and twice in the second). Would it be through selection mode? I've already tried all of them.

That's my syntax:

<block compatibletest1>
/ bgstim = (targetAleft, orleft, attributeAleftmixed, targetBright, orright, attributeBrightmixed)
/ trials = [1=instructions;
3,5,7,9,11,13,15,17,19,21,23,25,27,29,31= noreplacenorepeat(targetAleft, targetBright);
2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,32 = noreplacenorepeat(attributeA, attributeB)]

block compatibletest2>
/ bgstim = (targetAleft, orleft, attributeAleftmixed, targetBright, orright, attributeBrightmixed)
/ trials = [
2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,32,34,36,38,40,42,44,46,48,50,52,54,56,58,60,62,64 = noreplacenorepeat(targetAleft, targetAleft, targetBright, targetBright);
1,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33,35,37,39,41,43,45,47,49,51,53,55,57,59,61,63 = noreplacenorepeat(attributeA, attributeA, attributeB, attributeB)]

Let's take <block compatibletest1>. The items in your targetA, targetB, attributeA, and attributeB stimuli are sampled randomly without replacement. I.e., with 8 items per category, if you want each item to be sampled exactly once during the block, you need to run 8 targetAleft trials, 8 targetBright trials, 8 attributeA trials, and 8 attributeB trials. Your code doesn't do that, it runs too few targetAleft / targetBright trials. The code ought to read:

<block compatibletest1>
/ bgstim = (targetAleft, orleft, attributeAleftmixed, targetBright, orright, attributeBrightmixed)
/ trials = [1=instructions;
3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33= noreplacenorepeat(targetAleft, targetBright);
2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,32 = noreplacenorepeat(attributeA, attributeB)]
...
</block>

i.e. you want 16 target trials, with targetAleft and targetBright sampled in equal proportions, resulting in 8 trials each.

3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33= noreplacenorepeat(targetAleft, targetBright);

The same reasoning applies to <block compatibletest2>.

In addition, you can reset the various stimulus elements' selection pools at the start of the block.

<block compatibletest1>
/ onblockbegin = [text.attributea.resetselection();
text.attributeb.resetselection();
text.targeta.resetselection();
text.targetb.resetselection();
]
/ bgstim = (targetAleft, orleft, attributeAleftmixed, targetBright, orright, attributeBrightmixed)
/ trials = [1=instructions;
3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33= noreplacenorepeat(targetAleft, targetBright);
2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,32 = noreplacenorepeat(attributeA, attributeB)]
...
</block>

That way you can guarantee that all 8 items are available and free to be sampled at the start of the block.