I'm actually referring to the learning aspects of bitcoin
You need to learn about the wallet aspect so that you don't store or keep your coins in a centralized exchange like Binance which is the most popularly used. You can use electrum wallet, since is a non custodial wallet which you are in total control of your keys. If you store your coins in exchange or in a centralized platform,you are no longer in full control of your bitcoin anymore but they are because they are keeping your bitcoin in their own custody and not in your custody and don't forget these centralized platform are not to be trusted for so many reasons. They can give out your information to government or sell out your information to whoever is ready to pay for it. Bitcoin was created for maximum privacy for you to be anonymous as an identity.
If you have a wallet,the next thing is to back up your seed phrase and keep them in different location away from where people can have easy access to,if not if someone sees your seed phrase he can use it to get full access to your wallet and will steal all your bitcoin
I believe you have a trust wallet as it is the most commonly used wallet for holding funds and assets.
If you have already put your amount of BTC you want to withdraw the you click on continue, it would take you to the next page which is where you would see the settings at the upper right corner facing you. To set the fee, you will have to click it and reduce or adjust the fee yourself as it suits you for your transaction
Trust wallet is not advisable to use,it is vulnerable to attack and can be compromise. We have seen reports on this in the forum that trust wallet platform is responsible for the return of stolen funds from the victims wallets .You can use any of these wallets electrum or blue wallet.
Everybody have their own different challenges in their bitcoin journey,my challenge might be different from yours but it is how we understand bitcoin that we will also be faced with the challenges.