I am a strong believer in "answers are in the details" and "not taking anything for granted", so please excuse all the questions whose answers will help me help you.
Premiere Elements 14/14.1 on what computer operating system?
How are you importing the file into the project - what Add Media choice are you making?
When you have imported the file into Expert workspace's Project Assets are you allowing the file's audio and video conforming to complete before you drag the file to the Timeline tracks? Look to the lower right of the workspace for the appearance of a progress bar for this type of activity.
What are the properties of the file (video and audio components) that you are importing into your Premiere Elements project? Is the file from a device or screen capture program that records with a variable rather than a constant frame rate? If the file is from a camcorder, telling us the brand/model/settings for the camcorder that recorded the file typically gives us the file properties information needed for troubleshooting. I am looking for video and audio compression (Stereo or 5.1 channel), frame size, frame rate, interlaced or progressive, file extension, pixel aspect ratio. When previewing your trims in the Edit area monitor, is there an orange line above the Timeline content trims et al.?
After your file is on the Timeline track, go to File Menu/New/Project where you should be greeted with the new project dialog, Please tell us what is listed there next to Project Settings. After you get that information, then cancel out of there to get back into the project's workspace. I am trying to relate file stereo or 5.1 channel with appropriate set for project preset.
Would you characterize the sound issue as losing sound or audio out of sync with its video?
Of that 16 GB RAM installed, how much of that is available? How much free hard drive space? Where are the source media stored on the computer hard drive?
Let us start here and then decide what next based on the details in your reply.
Any questions or need clarification on the above, please do not hesitate to ask.