I finally figured this out! It was really hard to find the element in the code. (This is on a 7.1 site.)
This worked for me for the heading:
.sqs-block-image .design-layout-poster .image-title h1 {
font-family: Arial;
color: #000000 !important;
}
For the Sub-Title, just switched h1 to p:
.sqs-block-image .design-layout-poster .image-subtitle p {
font-family: Arial;
color: #000000 !important;
}
The font-family did not need the !important flag, but the color did.