Retract and set the shoulders
If your blades slide forward, the front delts take the load. Pinch your shoulder blades together and down into the bench and hold that position through the whole set.
Your shoulder blades are not retracted, your elbows flare too wide, and you likely flare or shrug so the front delts take over.
Feeling bench in your front delts means the load has shifted off your chest onto your shoulders. Pin your shoulder blades back and down and keep them there, set a slight arch so your chest is the high point, and tuck your elbows to roughly 45 to 75 degrees instead of flaring to 90. Lower the bar to your lower chest or nipple line, not to your neck, and keep the shoulders back rather than rolling forward.
If your blades slide forward, the front delts take the load. Pinch your shoulder blades together and down into the bench and hold that position through the whole set.
Elbows flared to 90 degrees and a bar path to the neck load the shoulder joint. Tuck elbows to around 45 to 75 degrees and touch the bar to your lower chest so the pecs drive the press.
A slight upper back arch makes your chest the contact point and takes strain off the shoulders. Keep your upper back tight and feet planted so you press from a stable base rather than pushing with the delts.
If bench causes sharp or pinching shoulder pain rather than just poor muscle feel, stop and see a physio, as that can signal an impingement or rotator cuff issue.
Your shoulder blades are not retracted, your elbows flare too wide, and you likely flare or shrug so the front delts take over.