Hey Michelle, generally I would say try not to have dollars at all. However if you are not interested in any alt coin and Bitcoin is going down (and the dollar is going up ) - then sell to dollars.
I think I am so long in the game now that I hate having anything in dollars because I know they generally go down against crypto coins.
The thing to think of is the general name of the game is to gain more Bitcoin or other Altcoin that you believe in.
By the way try to keep the bare minimum in your exchange account and make sure you have the 2FA id.
Do not save your password in your browser but write it down and type it in each time.
There are hackers around big time now and weak accounts are being targeted:
Change your email to one that is fairly long with Uppercase, lowercase and numbers with the odd "@" and "%" thrown in at the end. For example M1ch311ec@rt3r+++ (don't use that one lol)

I recently got hacked myself and had to update everything. I lost money but luckily I had sent a lot out already but it is not a nice experience.
I have a friend who is good on security and said the guys that hacked me were pros. He said I was more diligent than most but I was tired and got suckered with a false google page. I didn't check to see if the little lock was there. I mean think about that McAffee fellow, he is generally known to be the best security guy in the world and he lost $50,000 dollars when someone hacked is email. He was tired at the time too. So if it can happen to him ...
That is why security is the biggest issue with Bitcoin today and for tomorrow.

Get a free backup account with protonmail.com that has encryption software. The game is changing. When I started the money was tiny so hackers were not interested but now it as become big. I was foolish and did not update my email passwords to longer and more complex- You are a lovely lady Michelle and I would not wish for you to experience what I had too. I was sick for a day and could not eat. Its not the loss of money its the feeling of invasion of privacy that hurts.
Anyways I don't wish to scare you or put you off but I just wish someone had given me the heads up and reminded me things are changing. Glad it happened now though and not three years down the line when the alt coins are worth a fortune. One doesn't kill us makes us stronger I guess - send me some of your positive energy : )