Hello There,
Thanks for updating in! To resolve this issue, please add the following css code in the customizer, Appearance > Customize > Custom > Edit Global CSS
.soliloquy-container .soliloquy-prev,
.soliloquy-container .soliloquy-next {
background-size: contain !important;
}
This code will make sure that your arrow images will always be contained in the container for the arrow. The result would be like this: http://prntscr.com/ec9pa0
Hope this helps.