Is there anyway to make that the part where you enter your credit card information is open by default, instead of the part where you enter your paypal information?
I
for people reaching here from google and still cant manage to solve it , there are several key factors to this :
PayPal parameters: if you look at PayPal's API there are 3 relevant fields: LANDINGPAGE, USERSELECTEDFUNDINGSOURCE, SOLUTIONTYPE .
Not sending email parameter. change email parameter to '' (blank) . if you do send email parameter it will always open the login tab.
Cookies. no matter what you do , if the user have a PayPal cookie on his browser , the login tab will open by default (and the above parameters will be ignored) there is no solution for that (as far as I know) so make sure you check if it works with a cookie virgin browser.