> So it’s showing as down because it’s a 3% rate but rates are higher so it’s worth less in resale value?

Correct (this is how all bonds are priced).

https://www.fidelity.com/learning-center/investment-products/fixed-income-bonds/bond-prices-rates-yields

At its most basic, bond prices go up when rates go down and bond prices go down when rates go up but prices approach 100 (ie par) the closer you are to maturity.

So say you had two bonds from the same issuer and same maturity. One has a 4% coupon and one has a 6% coupon. Prevailing rates at 5%. The first bond will sell at a discount while the second sells at a premium. The yield to maturity for both will be the same, however so it doesn’t matter which you buy.