Thanks for reaching out.
The reason why this is happening is because the 'Allow partial submissions' option is enabled in your Survey Settings.
This option lets respondents pick up where they left off in a survey by using the same weblink. So when they click the same link, they'll be taken to the question they had stopped at, skipping the welcome page.
This option can be disabled by clicking Config (gear icon) on the left navigation bar of your survey.
Under Configurations, disable the 'Allow partial submission' toggle and click Update to save your changes.
Hope this was helpful! :)