If it’s okay to make straight characters gay, then is it
It definitely feels like people who make a gay character bisexual do it so they can make that character get with someone of the opposite sex; at least the stories I've seen in my main fandom it's done as a way to write off a character's lesbianism as a phase or something purely sexual (for male partner's entertainment) a worryingly amount. Early desire is mysterious, hilarious, often shameful—I wanted to explore how these feelings could track through a life. I outlined a young infatuation and a later love affair, which circle each other through time and memory in a widening spiral.
Why can people change straight characters to LGBT, but not
Can straight people write queer? Firstly, can straight people create LGBTIQ+ characters? To get some perspective on the matter, three writers who identify as queer give their opinions. Writer and Now Novel coach, Nerine Dorman says, “I'm fine with it. Just as I'm fine with queer folks writing straight characters. This notion that you can only write what you personally know is rubbish. So. Discussion in ' Entertainment and Technology ' started by caden , Jul 6, Empty Closets. Beyond stereotypes
Tips for avoiding stereotypes and tokenism, and presenting more interesting, complex, three-dimensional queer characters. She offers an online course, Story Medicine , designed to help writers use their power as storytellers to support a more just and verdant world. It was a lively and far-ranging discussion. 
Beyond Tropes
I think these days they include LGBT+ characters just to fill a quota, and I agree with @Loves books about some characters in series suddenly changing from hetero to bi or lesbian/gay. I also agree that sexuality tends to be the main focus of the characters created, rather than it just being about a character who just happens to be LGBT+. Which is bullshit. Queer people have all kinds of personalities — just like straight and cisgender people.
Non LGBT+ writer writing LGBTQ+ characters
Forcing gay relationships on otherwise straight characters. This happens a lot in fanfiction – characters who are established by the actual work as being straight suddenly having a revelation and realizing how horrible the opposite sex is and becoming gay – or even taking a character’s gender expression and running amok with it, deciding. You might want to do some research, if you don't identify as queer, and you will want to avoid the tropes mentioned below. The reason was that it was going to be showing the first lesbian kiss on prime-time TV. Changing established straight characters to LGBTQ+ characters
My writing process is only semi-conscious. When I’m writing, I find myself making decisions based on previous decisions, following character logics, layering on more thoughts than I can hold in my mind at one time. Characters and meaning build up to something beyond my grasp. . Queer Eye for the Straight Writer
Most likely because of the representation issues. Fewer gay characters in media compared to straight characters, so making an explicitly gay character into a straight character is seen as erasure of the character's sexuality. Just like it is looked down upon to turn a black or Asian character into a white character. . 
Is it wrong for me to write fanfiction portraying a gay
There is this anime I really like and one of the main characters is an effeminate male who is somewhat queer coded. He is very popularly shipped with another main male character, and the show itself is known for generally being kind of queer coded even if there are only a handful of explicitly gay characters throughout the series. .