Here's a few things to be aware of.
Assuming you have a Business account and the donation button is intended for fundraising. If you are not raising money for a cause, please choose another option. Nonprofits must verify their status to withdraw donations they receive. Users that are not verified nonprofits must demonstrate how their donations will be used, once they raise more than $10,000 USD.
Next, the answer to your question is Yes however, if you want a Donation button with multiple preset amounts, you can't create it using the button creator in your account. The button creator can only generate 1 fixed amount per button - this is OK if don't mind having several buttons but, another option is if you want a cleaner look is to have 1 button with multiple amounts. A button like that requires some custom coding with possibly a script to manage the logic - then for example, you could have radio buttons. When creating your own button code, you have a lot more freedom as to what you want it to do.
If you plan on going with 1 button with 1 fixed amount and you want to change the amount. You can do that manually providing you're not saving the code to the PayPal servers. If you plan to save the code to the PayPal servers, you have to go back to My Saved buttons in your account and edit the button, change the amount and save. You would not have to copy the code again to your web page as nothing has changed but the amount.
