Title color

The title color of the slideshow comes from the preset color of Helix3. You can find the preset color changing option here.

Extensions>>Templates>>Styles>>shaper_finance - Default>>Presets

You can change the preset majon color here.

Subtitle color

You have to do custom CSS to change the subtitle color. Change the following CSS and add that to the custom CSS option in Helix3. 

.sppb-slider-fullwidth-wrapper .sppb-slideshow-fullwidth-item-bg .details {
    color: #171313;
    margin: 20px 0 40px;
    display: none;
}