Hi techy76,
Welcome to the Mattress Forum!
Can you be more specific which mattress you purchased? If it was an Endless Comfort, there seems to be a few different locations carrying products using the Endless Comfort moniker, but they seem to be from different manufacturers. Can you share which model you purchased, and the foam layerings?
How do you know this item is manufactured in China? Can you share where you found out that information, as it’s not readily available online. If you have any other information (perhaps from the law tag) about the manufacturer or distributor, that would also be useful to share with everyone here on the forum.
Some people are more sensitive than others to the odors of new mattresses, specifically memory foam, and this can be worse in mattresses than have been compressed for very long periods of time (such as those shipped from overseas). Without knowing the components within your mattress, I couldn’t comment much upon that, except to state that it’s normal to allow a new mattress to air out a bit if you are sensitive to such odors, and it should dissipate after a few weeks.
Again, you’re not providing any meaningful specific information about the product you chose for me to provide commentary or assistance. In general all foams will soften a bit over time, especially within the first few months or so of use when they use their “false firmness”, and it is common for floor models to be softer than the new version of the mattress when it is taken home, even for compressed boxed bed products.
Toppers can be a viable alternative to replacing a mattress as a method to provide extra surface comfort. The information in post #2 here and the topper guidelines it links to can help you with selecting a new topper.
Phoenix