React Native Video Subtitle Position

Question

             <Video
                  ref={(ref) => {this.player = ref }}
                  source={{ uri: this.state.url}} 
                  paused={this.state.paused}
                  style={this.state.isFullScreen ? styles.videoFullScreen : styles.videoNormal}
                  resizeMode="contain"
                  onLoad={this.videoOnLoad.bind(this)}
                  onProgress={this.videoOnProgress.bind(this)}
                  onEnd={this.videoOnEnd.bind(this)}
                  onBuffer={this.onBuffer.bind(this)}
                  textTracks={this.state.subtitles}
                  selectedTextTrack={{
                  type: "title",
                  value: this.state.selectedTextTrack,
                  volume:{volume}
                }}
                />

These are the props which i have utilized in my code. I checked the documentation for the text track position but was unable to find any. the default position of the text track is the top. i want to display the subtitles on the bottom. How can i do it? How the subtitles currently display is displayed below in the image.