You may remember when studying the past tense that verbs ending in CAR GAR or ZAR had spelling changes in the YO form.
In the Spanish subjunctive, those same spelling changes happen only in ALL the verb forms.
For verbs ending in CAR like buscar, the C changes to a QU.
busque busquemos
busques
busque busquen
for verbs ending in GAR like pagar, the G changes to GU.
pague paguemos
pagues
Pague paguen
For verbs ending in ZAR like cruzar, the Z changes to a C
cruce crucemos
cruces
cruce crucen
Just like in the preterite, imagine a ZCAR in a CAR screaming "GARrrrr" but instead of driving through only the YO forms, he is completely out of control ( so is the subjunctive in my opinion) and he is driving through all verbs forms.