Signs of Fourier coefficients of cusp forms at integers represented by an integral binary quadratic form

In this article, we establish that there are infinitely many sign changes of Fourier coefficients of a normalised Hecke eigenform supported at positive integers represented by a primitive integral binary quadratic form with negative discriminant whose class number is 1. We also provide a quantitative result for the number of such sign changes in the interval (x, 2x] for sufficiently large x.