So it looks to me like they are hungry and need to be fertalized. You have them in a fairly small planter for a squash with what looks like heavier materials in the soil. Add a potting mix with some aged chicken maneur or a good rich organic liquid fertalizer and make sure you are watering them enough. Next year you need a much bigger pot for cucumbers like a wine barrel, or put them directly in the ground full sun. They like a lot of water & don't do well in the cold at all. If their roots are cramped they will put out tiny flowers. Since the yellowing is around the edges mostly it is likely a nutrient, water or ideal temperature defficiency. If it is the very beginning stages of powdery mildew then you can buy a foliars spray bottle and dilute milk, water & dawn dish soap to spray on the leaves, add a bit of neem oil to repel pests. Spray it on at a cooler time of the day without washing it off so it doesn't burn them. Reapply every 10 days as needed. When it sets fruit ring with crushed egg shells to repell snails and slugs. The smaller flowers are male and larger ones are female. You can hand pollenate the female flowers from the male using a qtip or paint brush if you have less pollenators. I usually harvest those smaller cucumbers when they are immature for the best pickles. Green ones that are larger for fresh eating. When the plant is stressed it will try to ripen fruit wierdly & sometimes you just get a dud or misshapen fruit. They turn that orangy yellow color when they are overripe. You can still eat it, but it won't taste as good, or you can save the seeds from it for next year and make great compost from the rest. Just harvest the other fruit sooner. Don't get discouraged as each step is a learning curve and even the wierd fruit help you the next year either by growing nutrients by putting them right back in the planter bed, composting or obtaining you more free seeds. Don't transplant them at this point as squash have delicate roots and you will likely just lose them. Feed them and water them more.
