why viper ingores the "" in a yaml

[LoveXayah]

while i use viper to update a value of a yaml and use WriteConfigAs to save the result,actually it works ,but the "" miss,like below

[LoveXayah]

like test.yml below
a : "cat"
b:
--c=d
viper.Set("a","dog")
viper.WriteConfigAs("test1.yml")

it will return like
a: dog
b:
--c=d
and the file will be indented incorrectly, when i work by ansible,the yml needs "" to recognize variable，if there's a way to handle that?