Scrolling issues when browser window is resized

Hi all. I am new to Figma and need some help with a scrolling issue. I have adapted a site from existing files with a fixed menu on the left and a scrollable area on the right of my frame. I have main menu buttons which link to frames with drop down sub menus. The sub menus scroll vertically to anchor points within the frame and work as I need them to on a wide screen with a full width browser window. My issue is when I resize the browser window or view my prototype on a smaller screen (laptop) the main scrolling frame scrolls across to the left over the menu as opposed to just scrolling vertically. Is there something simple that I need to do to keep this frame fixed in it’s horizontal position. Thanks for any help