By Plural words, Tenses

Hi, Sometimes I see phrasal cases where adjectives in front of a noun seem to warrant it to be plural but ends up being the case of shared adjectives. Is this one? Can you help me to clearly distinguish similar situations? both singular and plural tense -- When should 'tense' be 'tenses'? ...

I have also been a business studies teacher all my life. I assumed that because you have various customers, they might each require a different solution for their individual needs. Therefore I used the plural tense for solutions to match the plural word "customers" - but not knowing exactly...